Calling the United States “the indispensable nation,” President Joe Biden used his second Oval Office address to argue that America has the resources and the responsibility to arm Ukraine and Israel “for as long as it takes.” Absent from the speech was Taiwan — the other U.S. partner in desperate need of U.S. weapons — along with any mention of the tradeoffs that will be required to balance Washington’s competing demands.
As our analysis shows, the most significant potential tradeoff isn’t between Ukraine and Israel, which have different armament needs, or between Ukraine and Taiwan, which have more overlap but still have different priorities. Rather, the tradeoff that Washington should be focused on is between Israel and Taiwan. In the best-case scenario, if the Israel-Hamas conflict remains limited, Washington may face no tradeoff at all. But if fighting expands to include Hizballah or direct conflict with Iran, the United States will be unable to avoid making hard choices about how to allocate arms transfers and military aid between Ukraine, Israel, and allies in the Indo-Pacific.
While there are important areas of overlap between the military needs of Taiwan and Ukraine — especially when it comes to air defense and uncrewed aerial systems — their many differences made resourcing both marginally sustainable. Ukraine’s highest-priority needs include heavy artillery, ammunition, tanks, short-range missiles, and mobile air defense, while Taiwan has much more need for anti-ship missiles, naval mines, long-range missiles, and more advanced, longer-range air defense systems. Adding aid to Israel changes this calculus. Israel’s needs overlap somewhat with Ukraine’s but more extensively with Taiwan’s and those of other Indo-Pacific allies. This means that a commitment to fully aiding Israel could leave Taiwan and other U.S. allies and partners in the Indo-Pacific facing longer delays for systems they require and could leave U.S. forces ill-equipped to counter China.
To avoid putting Indo-Pacific allies in this position, Washington should confront the resource constraints and necessary tradeoffs it faces on military aid. The Indo-Pacific is America’s top defense priority, according to Biden’s National Defense Strategy, and Washington faces greater medium to long-term escalation risks there if it cannot effectively deter China. Moreover, the military threat posed by China is substantially greater than that of Hizballah or Iran. What’s more, Taiwan’s current military capabilities fall well below Israel’s.
As a result, Washington should place clear boundaries on its aid to Israel to preserve capabilities that are essential to deterring China in the Indo-Pacific. First, the United States should take off the table key systems needed by Taiwan, other Asian allies and partners, and U.S. forces in the Indo-Pacific. These include long-range precision and anti-ship missiles, air defense systems like Stingers, Patriots, and terminal high-altitude area defense, and a substantial percentage of uncrewed aerial and naval systems. Second, the United States should be explicit with Israel in private about the hard limits of U.S. materiel support, including capabilities, amounts, and duration, thereby allowing Israel to develop sustainable defense plans. Finally, policymakers should define an exit strategy for eventually winding down the additional emergency aid provided to support Israel in this crisis period.
Scenario 1: A Limited Gaza Incursion
If Israel’s campaign in Gaza remains limited to a multi-month offensive targeting Hamas, the United States will have little trouble supporting it without compromising aid to Ukraine or Taiwan.
With few exceptions, the capabilities in demand in Ukraine are not needed by Israel for operations in Gaza, and the overlaps that do exist are probably manageable. Israel has so far relied most heavily on its Iron Dome air defense system with Tamir interceptor missiles and air-launched precision-guided munitions including small diameter bombs and gravity bombs equipped with joint direct attack munition kits to conduct thousands of airstrikes on targets in the Gaza Strip. The United States has provided additional quantities of these weapons to Israel in recent weeks, but they have not come at the cost of Ukraine or other U.S. foreign policy priorities.
Israel is the only country operating the Iron Dome system, and Ukraine does not have the F-15 aircraft required for air-launched small diameter bombs. The United States has promised a ground-launched version of the small diameter bomb to Ukraine (and Taiwan), but these are a new capability and have not arrived. Ukraine uses joint direct attack munitions, which turn unguided weapons into guided ones, but they are relatively cheap and easy to produce in large quantities. As it continues its airstrikes, Israel might use other air-launched precision-guided munitions, such as the Hellfire missile – which the United States has also reportedly provided in recent aid shipments – but with excess capacity and the proven ability to surge production, it should not be difficult to meet Israel’s needs for this weapon.
For a conflict confined to the Gaza Strip, Israel should have little need for most capabilities in shortest supply and highest demand in Ukraine. For example, advanced air defense systems like the Patriot have missiles that are too expensive to expend on Hamas’ less sophisticated rockets. Ground-launched precision-guided weapons, such as Army Tactical Missile Systems, have a range longer than what is needed for strikes in Gaza. Israel could make use of Stinger missiles, which have been in high demand in Ukraine, but these are in such short supply in U.S. stocks that the United States is unlikely to be able to provide them to any partner in the near term. On the other hand, requests for additional tanks, artillery, armed drones, or aircraft are unlikely. Even if the Hamas-Israel conflict expands to include ground incursions, the Israel Defense Forces likely have sufficient systems of their own.
A more extensive ground operation into the Gaza Strip will create additional defense needs. This includes increased demand for the 155mm shells that Ukraine burns through at a rate of 6,000 per day — far above U.S. production capacity of 28,000 per month. Compared to Ukraine, however, Israel’s 155mm ammunition requirements are likely to be limited. For example, in the 51-day Israeli operation in Gaza in 2014, the Israel Defense Forces reported using about 35,000 artillery shells. This is comparable to rates of fire for U.S. forces operating in urban environments against the Islamic State.
Washington has already provided Israel with of tens of thousands of these shells, though the Pentagon pushed back onclaims these were rerouted from Ukraine to Israel. Combined with a sizeable ammunition order Israel placed earlier this year and access to what remains in the U.S. stockpile prepositioned on Israeli territory, this may be enough to meet Israel’s needs in Gaza. Meeting Israel’s ammunition needs may come at some marginal cost to Ukraine’s operations, but given that Ukraine’s counteroffensive is largely stalled, these effects should be small and temporary.
Scenario 2: An Expanded War with Hizballah
An expanded conflict that includes Hizballah, however, would dramatically increase Israel’s military requirements and potential requests for assistance from the United States. This would put real but not unmanageable strain on aid to Ukraine. However, in this scenario, the impact on military assistance and deterrence in the Indo-Pacific should be the primary concern.
Hizballah is thought to have somewhere between 20,000 and 50,000 fighters and a stockpile of around 150,000 missiles, including relatively advanced precision-guided and short-range ballistic and anti-ship missiles and drones that could overwhelm Israeli air defenses and devastate critical infrastructure. In its 2006 war against Hizballah in southern Lebanon, Israel relied primarily on long-range fires — hitting as many as 7,000 targets using 19,000 bombs and 2,000 missiles — supplemented by a more limited ground campaign and naval blockade with sea-based strikes. Facing a stronger and better armed Hizballah today, the Israel Defense Forces would almost certainly respond with increased airstrikes and artillery fire, creating additional demands for precision-guided munitions and ammunition. Israel has also surged tank units to its northern border, suggesting a ground operation might be possible as well.
The United States could probably supply Israel with the short-range weapons it would need to take on Hizballah. But a longer or more intense campaign than in 2006 — a likely reality, given that Hizballah is stronger than in 2006 — could strain existing stocks, especially for systems like the Hellfire that have relevance in both Ukraine and Taiwan. Tradeoffs would become more difficult if Israel requests longer-range air-launched systems such as the joint air-to-surface standoff missile or the joint standoff weapon to strike Hizballah targets in Syria, where more modernized air defenses are capable of intercepting Israel’s fighter jets and air-launched munitions. Israel might not need many of these longer-range missiles. But they would be central to any Indo-Pacific campaign, and U.S. stockpiles are quite limited — by some estimates already below what would be needed for a Taiwan contingency — so even a minor diversion could detract from both deterrence and warfighting capability in the Indo-Pacific theater.
Meeting additional demand for 155mm ammunition would be harder. Over the course of the 34-day 2006 war with Hizballah, Israeli forces fired nearly 150,000 artillery rounds, including 155mm and other variants. With Hizballah stronger now, the Israel Defense Forces might need to increase their rate of artillery fire. At the very least, a ground operation that takes several months could increase Israel’s 155mm ammunition needs by over 100,000 rounds, which would undoubtedly force tradeoffs with supplies sent to Ukraine. Once again, the stalemate in Ukraine and Israel’s smaller needs should be factors in allocating resources across the two countries.
Israel’s need for air defense is also likely to increase if the war expanded to include operations against Hizballah. To protect against Hizballah’s larger and more advanced arsenal of missiles, Israel relies on layered air defenses that include the David’s Sling and the Arrow 3 anti-ballistic missile. But even these advanced systems might be overwhelmed by Hizballah’s likely high rate of fire and cruise missiles. Both systems are produced in Israel, so the United States would not be able to backfill these systems directly. To fill any gap, however, Israel might request U.S. Patriot air defense systems — which are already in short supply. Not only are they needed in Ukraine, but they are also high on the list of capabilities required in the Indo-Pacific, whether for Taiwan’s asymmetric defense or for U.S. installations in the region. Sending them to Israel instead would leave both vulnerable.
Finally, as it did in 2006, Israel also might try to blockade Lebanese ports to limit the flow of weapons into Lebanon. Israel has a supply of domestically produced anti-ship missiles it could use to support this operation, but depending on the scope, it might request more, like the Harpoon missiles that Israel previously purchased from the United States. With Taiwan waiting for 800 Harpoon missiles and other allies in the Indo-Pacific region interested in this capability, meeting an Israeli request for this or similar systems would create difficult tradeoffs.
Scenario 3: A Direct Conflict with Iran
Iran has traditionally relied on proxies like Hizballah, but as Israel’s operations against Hamas intensify, there is a risk the Israeli-Iranian “shadow war” may become more open. If this occurs, additional Israeli military needs — for example long-range strike and air defense capabilities — would impact some U.S. military assistance to Ukraine but could have devastating implications for Washington’s Indo-Pacific allies and partners.
Iran arguably has the most versatile and largest arsenal of rockets and missiles in the Middle East. This is comprised of cruise and ballistic missiles, long-range missiles that can reach Tel Aviv, a large land- and sea-based paramilitary force, and possibly advanced air defense systems acquired from Russia.
To overcome Iran’s advanced air defenses, Israel could request additional long-range precision-guided munitions (most likely air- and sea-launched) from the United States, including the joint air-to-surface standoff missile, Tomahawk, or Standard Missile-6, among others, along with advanced uncrewed aerial systems with strike capabilities. To counter any threats from Iran’s sea-based paramilitary forces, Israel might need additional uncrewed surface and underwater vessels and a sizable stock of anti-ship missiles, including possibly the long-range anti-ship missile and Harpoon missiles. Finally, a direct conflict with Iran would pose further air defense challenges. Since Israel would require time to build up its stockpiles of Arrow 3 missiles, it might request U.S. Patriot systems or even temporary use of a U.S. terminal high-altitude area defense system to protect against Iran’s arsenal of ballistic and cruise missiles.
Except for the Patriot air defense system, these capabilities are not in high demand in Ukraine, but they are essential for the Indo-Pacific theater and in short supply there. For example, U.S. forces and allies and partners would rely heavily on long-range strike assets to target Chinese air, naval, and potentially mainland assets. The Pentagon has prioritized increasing its production of these weapons, in particular the joint air-to-surface standoff missile and long-range anti-ship missile, but these efforts would be undone by a diversion of substantial quantities of either to the Middle East. Uncrewed air and naval systems will also be valuable for U.S. forces to counter a Chinese invasion fleet in the Taiwan Strait or Chinese forces in the South China Sea. The same systems will be central to Taiwan’s asymmetric defense. Finally, given China’s large stockpile of advanced weapons, air defense of all kinds will be at a premium in the Indo-Pacific, and the loss of even moderate numbers of these systems to the Middle East will have a negative impact on the U.S. posture in Asia.
The Rationale for Prioritizing Taiwan
There are two main reasons why military assistance to Taiwan should be prioritized over aid to Israel. The most important is that the U.S. interests at stake in the Indo-Pacific are much greater than those in Middle East. The Biden administration has repeatedly identified China as the most significant U.S. competitor and prioritized the goal of deterring Chinese aggression in the Indo-Pacific as the focus of U.S. defense policy. The United States has significant economic interests in the region and a strategic interest in deterring China from seizing Taiwan, which could shift the balance of power in Asia and put pressure on U.S. alliances in the region. In contrast, U.S. economic and strategic interests in the Middle East are considerably narrower, especially given greater U.S. energy independence. A deterrence failure in the Indo-Pacific will have more severe consequences for the United States and should be more strenuously avoided.
In addition, U.S. assistance is both more needed in the Indo-Pacific and likely to have a greater impact on regional deterrence and escalation risks than it would in the Middle East. The military challenge China poses to Taiwan and other Indo-Pacific allies is substantially greater than the threat presented to Israel by Hizballah or Iran — especially since neither has shown much interest in escalation with Israel to this point. This is true not only because China’s military capabilities greatly exceed those of Iran and its proxies but also because Israel has an advanced and well-stocked arsenalof its own supplemented yearly by nearly $4 billion in U.S. military assistance while Taiwan’s military capabilities are substantially weaker and in need of much investment before they will be sufficient to defend against Chinese attack. In this context, it makes sense to prioritize scarce resources toward the greater threat and need.
A Sustainable Path Forward
Instead of open-ended military assistance, Washington should provide narrowly tailored aid to help Israel increase its capacity for self-defense and reduce the most pressing threats presented by Hamas. Policymakers should make clear to Israel that capabilities defined as central to Indo-Pacific deterrence will not be provided. This would include all long-range strike systems, anti-ship missiles, air defense systems including Stingers, Patriot, and terminal high-altitude area defense, and a large portion of uncrewed air and naval platforms.
To keep these systems “off limits,” the United States will need to communicate the boundaries of its support privately to Israel’s war cabinet, specifying capabilities that it will not transfer and, for those that it can provide, the quantities that are available and on what timelines. U.S. leaders should make clear that the limits of U.S. support would grow tighter as the conflict expands, incentivizing Israel to avoid escalation, realistically plan its own operations given available weapons supplies, and make choices about how to invest in its own long-term security. Being clear about limits to military assistance upfront may also help reduce political pressures down the line, as the conflict evolves.
Finally, U.S. policymakers should begin planning their off-ramps for reducing emergency aid — that is, aid above the annual military assistance Israel normally receives from the United States. Ukraine, Afghanistan, and Iraq show the difficulty of reducing military assistance once it is in place. To prevent a repeat, U.S. policymakers should define indicators relating to Israel’s progress toward its military goals and defense industrial base development that would trigger a gradual reduction in emergency aid and return to the usual status quo. Policymakers could also consider using the Israel aid package now before Congress to further signal boundaries on emergency military aid. Given that Israel has most of what it needs to prosecute its campaign in Gaza and a robust defense sector, a smaller aid package could still signal U.S. political support for Israel’s highest-priority near-term needs, but with a clearer end point and less risk of pressure on the priority systems needed in the Indo-Pacific.
Some observers, seeing the United States unable to provide unlimited arms to an array of partners while also filling its own stocks to abundance, argue that the best solution is for the United States to massively ramp up investment to put its defense industrial base on wartime footing. This approach cannot meet near-term demands or address the root causes of delays and bottlenecks in U.S. weapons production. Furthermore, it is likely that demand will rise with increased supply, leaving the United States no better off.
The United States cannot escape the need to make tough choices when it comes to allocating scarce military aid. It should define narrow goals and carefully prioritize its means. The alternative is the real risk that the United States will be outmatched by a peer competitor in the Indo-Pacific because it let itself become overextended elsewhere.
Jennifer Kavanagh is a senior fellow in the American Statecraft Program at the Carnegie Endowment for International Peace.
Jordan Cohen is a policy analyst in defense and foreign policy at the Cato Institute.
Image: Chad McNeeley, Office of the Secretary of Defense Public Affairs
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