When looking through the lens of a military deployment, we can sometimes see the outlines of diplomacy. There was an example this week.

American troops landed in Israel with a “Terminal High Altitude Area Defense” (THAAD) battery to bolster defences ahead of a possible third Iranian missile attack if Israel retaliates for Iran’s October 1 attack.  It takes about 100 troops to operate the system. This tells us Washington D.C. is prepared to risk the safety of an extra 100 American troops, which poses the question: why?

There appear to be several reasons. Firstly, it’s clear that air defence munitions are running low in both the Israeli stockpiles, and the American ships from the 6th Fleet in the Mediterranean which helped shoot down missiles in the first two attacks. Secondly, the deployment of THAAD signals to Iran that the US is prepared to try and fill any gaps in Israel’s defensive shield. It also raises the stakes for a third strike as Tehran now knows it may kill American soldiers in a massive barrage. Finally, it’s thought that President Biden agreed to send the system in return for Prime Minister Netanyahu agreeing not to hit Iran’s nuclear sites. The thinking is that if Israel goes for military and (limited) economic targets, Iran may not feel compelled to return fire. If it does respond forcefully, the Americans will be better placed to help defend Israel and their own troops in the region who may come under attack from Iran’s proxies in Iraq.

During the first attack, in April, the Israeli defences managed a 99 per cnt interception rate success against Iran’s 200 or so missiles and drones (it helped that Iran signalled its intent). But October 1 saw a change. There were fewer (slower flying) drones, and more seriously quick Fattah hypersonic missiles. Almost three dozen hit the Nevtim airbase which houses Israel’s F-35 jets, and one exploded just several hundred yards from the Mossad HQ in northern Tel Aviv. 

The more missiles fired simultaneously, the harder it is for the Israeli air defences to shoot them down. The 6th Fleet ships used up dozens of their SM-32A missiles in April and earlier this month. They may not have been resupplied and need to conserve a certain amount in case of other threat – hence the arrival of THAAD. 

It will fit into Israel’s multi-layered defence system. This uses Iron Dome against short range rockets, David’s Sling for heavier munitions fired from longer range, and the Arrow 2 and Arrow 3 systems for long range high altitude ballistic missiles. The system is programmed to ignore missiles which AI says will land in open ground, so the more which are fired into populated areas, the more interceptors are required. 

The US has seven THAAD batteries. Each has 6 launchers, and each launcher has 48 missiles meaning 48 missiles could be shot down. Unlike Arrow 2 which fires a warhead which explodes near its target (knocking it off course), THAAD hits the actual missile. The radar system which sends THAAD its targeting information can track targets more than 1,500 miles away which means one positioned in Israel can spot anything launched from Iran almost immediately.

The THAAD flown to Israel is now being meshed with the American missile interception radar base in the Negev, and with the Israeli system. A battery has been sent twice before; once in 2019 for training purposes, and once in 2023 after the Oct 7 Hamas attack. Nevertheless, it is an unusual move. 

Iran is busy breathing fire. The Commander in Chief of the Army, Abdolrahim Mousavi, said this week that if Israel attacks Iran, then Tel Aviv and Haifa “will be erased in seconds”. They probably wouldn’t be, but in the event of a mass attack, including missiles fired by Hezbollah in Lebanon, and the Houthis in Yemen, serious damage and loss of life is likely.

THAAD has been sent to deter such a scenario, and, if deterrence fails, to limit the effects.