Patriot: The high-cost/high-capability Patriot missiles ($4.1 million each) are well suited for attacking adversary aircraft, cruise missiles, and ballistic missiles, such as the ones Iran possesses. However, the missiles are too scarce and expensive to use against Hamas's inexpensive artillery rockets.

Iron Dome: Iron Dome is the ideal system for defense against Hamas artillery rockets. The system was designed to counter the militant rocket threat, is not expensive, and is widely fielded. The missiles are coproduced by the United States and Israel. It is unsurprising, therefore, that Israel is reported to have requested more Iron Dome missiles. The United States can expedite production of missile components and fund Israeli production of additional systems. The United States also has two Iron Dome batteries it used for testing and could return to Israel.

Stinger/Avenger: Stinger is an infantry portable anti-air missile; Avenger is the truck-mounted version. The system is widely used around the world and effective against drones and aircraft. However, inventories are extremely limited, and production is slow. The United States has given Ukraine most of its available inventory, and Taiwan has likely received some as part of the presidential drawdown of equipment authorized by Congress.

The United States cannot help much with Israel’s two domestically produced air defense systems. David's Sling is for medium and long-range interceptions, much like Patriot. Arrow is designed to intercept ballistic missiles, which Hamas does not have but Iran does.

Bringing in new systems like National Advanced Surface-to-Air Missile System (NASAMS) would take too long because of the need for training and setting up a logistics pipeline.

Q3: Is there anything beyond precision munitions that Israel might need?

A3: Yes, there are several other capabilities that Israel will likely need almost immediately.

• Intelligence support: Israel is certainly getting intelligence help from the United States, especially for hostage rescue. This likely takes the form of signals intelligence and overhead surveillance. For example, the United States may well be eavesdropping on terrorist conversations. Much of this will come from Middle East dedicated assets, but some might be diverted from Ukraine.
• Spare parts: In peacetime, some part of a military’s equipment, anywhere from 10 percent to 50 percent, is inoperable because of a lack of spare parts or maintenance time. A surge of spare parts would expand the effective size of Israel’s force by making more equipment operational. There will be some competition for these spare parts since U.S., Ukrainian, and, often, Taiwanese forces need the same parts.
• Uncrewed aerial systems: Israel already has many of these, but they are particularly helpful in built-up areas where finding the adversary is difficult but crucial. However, Ukraine also has a great need for such systems.
• Counter-Drone Systems: Islamic militants have been clever in adapting commercial drones and may have received some from the Iranians. The militants will likely use these to strike back at Israel as Israeli forces attack the Gaza Strip. Therefore, a network of counter-drone systems will be needed. The United States has a wide variety of such systems, mostly developmental. However, Ukraine needs these in large numbers to counter Russian drones, which spot for Russia’s powerful artillery.

The longer the war goes on, the more resupply Israel will need as equipment is destroyed and munitions get used up. Items not needed in the first few weeks may be needed after a month. Therefore, this list will grow over time.

Q4: How will all this be paid for, and how much will it cost?

A4: Annually, Israel receives $3.8 billion of military aid, but this will not cover the costs imposed by this war. As a result, there will almost certainly be a supplemental appropriation, and, indeed, President Biden has stated his intention to ask for one. The core element of the supplemental will pay to replace equipment and munitions sent to Israel during the war. The supplemental may also include funds to rebuild Israel’s military after the war, and to help Israel repair the damage to buildings and infrastructure.

There may be economic support as well. The call-up of hundreds of thousands of reservists in a country of nine million disrupts the economy. Further, the tourist industry, which Israel is highly dependent on, has collapsed and may take months or years to rebuild. The United States has provided economic assistance to Israel in the past and could easily resume such assistance in an emergency like this.

The full need will not be known until the war is over. The United States might provide an interim amount. As a benchmark, the initial Ukraine supplemental (March 2022) was $13.6 billion. Interim funding might be combined with the Ukrainian aid package, giving the latter an extra push towards enactment. An additional amount for Israel could come later and during the regular budget cycle if more was needed.

Q5: So can the United States keep Israel supplied, given the other commitments, or is this beyond what even a superpower can do?

A5: The preceding discussion indicates that the answer is yes, but with some difficult tradeoffs later. Israel’s needs are likely to be relatively small compared to what Ukraine has needed. The forces involved are smaller, and the war will likely be shorter. Israel's relationship with the United States is closer and longer standing. Therefore, Israel will get priority. The initial ask—as currently reported—does not conflict with Ukraine’s or Taiwan’s needs. SDB is available in large numbers, and neither Ukraine nor Taiwan uses the Iron Dome.

Nevertheless, as time goes on, there will be trade-offs as certain key systems are diverted to Israel. A few systems that Ukraine needs for its counteroffensive may not be available in the numbers that Ukraine would like. This will not force an end to operations but might become noticeable on the front lines if the war in Gaza continues for an extended period.

Mark Cancian (Colonel, USMCR, ret.) is a senior adviser with the International Security Program at the Center for Strategic and International Studies in Washington, D.C.