Why America's THAAD missile defense deployment to Israel is a 'gamble' in Iran conflict, analysts say

LONDON -- Around 100 U.S. troops will soon be on active duty in Israel to help defend the country against the potent missile threat from Iran and its regional allies, most notably Hezbollah in Lebanon.

They will be deployed with a Terminal High Altitude Area Defense (THAAD) battery; a $1 billion weapon sent to hotspots including South Korea, Guam and the United Arab Emirates to blunt the ballistic missile threat posed by America's adversaries.

The THAAD deployment is both a political and military signal ahead of Israel's expected retaliatory attack on Iran, in response to the latter's Oct. 1 ballistic missile barrage.

"I think we should view this THAAD deployment as for what it is, which is another visible statement of our commitment to the security of Israel as it deals with everything that's coming at it from Hamas and Hezbollah in Lebanon," Army Secretary Christine Wormuth said this week.

But committing American troops on the ground and scarce hardware to a potentially open-ended war in the Middle East also poses risks. Wormuth acknowledged that the Army's air defense forces are "the most stressed" of any other force in the service given the high demand for their systems.

"Missile defense buys you time, missile defense buys you flexibility to end the threat by other means," Thomas Karako -- the director of the Missile Defense Project at the Center for Strategic and International Studies, a Washington think tank -- told ABC News.

"But you have to go and make use of the time and the flexibility that it buys you," he added. "You can't just sit and play catch."

"If we're going to commit that kind of thing, we need to make sure that it is used well and that we communicate to the Iranians that they need to stop this nonsense," Karako said.

"The threat from the Iranians needs to come to an end, and sometimes escalation is a good thing if it means drawing something to a close as opposed to having a long-running attrition conflict," he added.

"It's a gamble."

Israel's anti-missile net

Lockheed Martin's THAAD is designed to stop short-, medium- and intermediate-range ballistic missiles, its munitions able to hit targets out to between 93 to 124 miles and at an altitude of 93 miles.

The interceptors are intended to hit missiles both inside and outside Earth's atmosphere during their final stage of flight.

The THAAD's capabilities are roughly equivalent to Israel's Arrow 2 system. Israel also uses the longer-range Arrow 3, alongside the medium- to long-range David's Sling system and the famed Iron Dome system for shorter-range threats.

As such, the THAAD does not necessarily represent a significant capability upgrade, Sidharth Kaushal of the Royal United Services Institute think tank in the U.K. told ABC News. Rather, "capacity is the more meaningful contribution," he said.

With Israel now facing the reality of massed drone, rocket and ballistic missile attacks, "every radar that can be there helping to light up the sky and put energy on incoming threats is going to be helpful," Karako said.

But the THAAD is limited in how long it can "play catch" for. Each battery is typically stocked with 48 interceptor missiles, according to a 2024 Congressional Research Service report. The system includes an advanced radar that tracks incoming missiles and guides its 20-foot-long interceptors. The truck-mounted launcher consists of eight tubes.

The first THAAD system was fielded in the U.S. in 2012, according to CSIS' Missile Defense Project. Lockheed Martin said in December that it had delivered a total of 800 interceptors to the Defense Department's Missile Defense Agency. There are only seven THAAD systems, with an eighth due to be delivered in 2025.

The missile-centric strategies of Hezbollah and Iran have put stress on Israeli-American defenses. During Tehran's Oct. 1 barrage, U.S. warships in the Mediterranean Sea fired around a dozen Standard Missile 3 interceptors and other weapons to defeat the attack, the Navy said.

"When the United States expends a dozen SM-3s in a day, or in an hour, as we did a week or so ago, that's a year's production," Karako said.

"These are very scarce resources and should not be thought about as being spent cavalierly. Because when our inventory is used up, it's used up for the United States globally."

It's a concern -- we're not producing the THAAD rounds in large numbers," he added. "It's a risk."

The drone threat

Surviving Hezbollah leaders have said the group is committed to facing down Israel's air and ground offensive. Hezbollah is still launching rockets and drones into northern and central Israel on a regular basis with some success.

Last week, for example, four Israeli soldiers were killed and 55 were wounded in a drone strike on a training base in the north of the country. Defense Minister Yoav Gallant vowed that the military would learn lessons from the "painful" attack.

The U.S. THAAD in Israel will be protected by Israel's layered defensive network. But drones, rockets and missiles can -- and already have -- slipped through.

The THAAD "is a very exquisite radar, it's a very powerful radar, but it's also a very big target," Karako said.

The system, Kaushal added, is "not designed to operate against low-flying targets such as UAVs and cruise missiles."

He noted a 2019 incident in which a North Korean drone was found crashed near a THAAD system in South Korea, having flown underneath its radar field.

The success of Israel's other air defense systems, Kaushal said, "will determine how safe THAAD batteries are against Iranian-Hezbollah efforts to target them."

ABC News' Luis Martinez contributed to this report.