Analysis: How long can Israel and Iran fight, and how is it impacting US stockpiles?

Israel and Iran are approaching one week of some of the most intense fighting ever witnessed between the two. But how long can the hostilities continue, and what kind of impact is the conflict having on US weapons stockpiles?

Analysts and current and former US officials believe the conflict is unlikely to develop into a long-term campaign. “It’s closer to days than months, and Iran has more problems than Israel,” a former senior American official said.

Israel has deeper stockpiles and more advanced military capabilities than Iran. Tehran, officials say, is not only facing weapons shortages, but also serious coordination problems after Israel killed several top generals and senior aides.

“This makes it much more difficult for Iran’s military to cooperate and launch attacks,” a second former official said.

Despite that, there are growing concerns in Washington over the depletion of US missile interceptors and other air defense systems, which have either been transferred to Israel or used by American forces to fend off Iranian missile and drone attacks.

“This [Israel-Iran conflict] is eating away at our reserves,” one of the former US officials said. But this person added, “time works against Iran more than against Israel.”

Over the last two years, the US military also used a significant number of munitions to counter Houthi attacks in the Red Sea. That continued until the Trump administration launched an offensive campaign targeting Houthi leadership and weapons infrastructure inside Yemen. The effort consumed large quantities of US missiles, including SM-2, SM-3, and SM-6 interceptors.

Meanwhile, the US defense industrial base has been under significant strain since the United States committed billions of dollars in weapons to Ukraine following Russia’s invasion. The monthslong Houthi campaign further depleted US stockpiles before the ceasefire was reached last month, putting a pause on the daily use of weapons in the region.

Michael Eisenstadt, the director of The Washington Institute's Military and Security Studies Program, said the US needed to be concerned about its weapons inventories not just because of the crises in the Middle East, “but in case a crisis with China or on the Korean Peninsula were to occur, in which ammunition expenditure rates are expected to be much higher.”

On Wednesday, Senate Armed Services Committee Chairman Roger Wicker raised the alarm during a hearing with the Pentagon chief and the top US military commander, as they reviewed the administration’s proposed defense budget.

“This is the most dangerous national security moment since World War II. Unconstrained, aggressive dictators are on the move. And, importantly, the character of warfare is rapidly changing,” Wicker said.

He also criticized the budget request, warning that it lacks the strategic investments needed to rebuild the US defense industrial base.
US defense of Israel

Israel’s ambassador to the US said this week that Iran possesses around 2,000 ballistic missiles. Israeli media reports suggest that about 400 of those have already been launched. Iran is also believed to possess an unknown number of lower-cost cruise missiles and drones, which it often uses in mass salvos aimed at overwhelming Israeli and US air defenses.

The US currently has at least one — possibly two — Terminal High Altitude Area Defense (THAAD) batteries deployed in Israel. These were used to help intercept Iranian missile attacks during last year’s escalation.

US officials told the Wall Street Journal that Israel is facing mounting difficulties in replenishing its interceptor stockpiles. The Israeli military depends on a multi-layered air defense architecture, supported in part by US systems, to manage sustained missile threats. This includes the Arrow 2 and Arrow 3 systems for intercepting medium- and long-range ballistic missiles, as well as David’s Sling and Iron Dome for short-range rockets and projectiles.

Eisenstadt said Israel was “burning” through its missile defense inventory. However, he emphasized that Israel’s ability to destroy Iranian missile launchers has helped reduce the number of incoming missiles, making the threat more manageable.

Whether or not the US joins direct strikes against Iran could further affect Israel’s need for additional interceptors.

“That said, Iran might nonetheless be able to drag out the war, but there might come a time when it no longer serves its interest to do so due to the damage being inflicted on its armed forces, military industries, and national infrastructure, and it could escalate… elsewhere to put pressure on Israel and the United States to end the war,” according to Eisenstadt.

On Wednesday, US President Donald Trump said he had not yet made a decision about attacking Iran. “I’m not looking to fight,” he said during remarks in the Oval Office. “But if it’s a choice between fighting and [Iran] having a nuclear weapon, you have to do what you have to do.”