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.

The first components of a U.S. missile defense system aimed at protecting Israel from attacks by Iran have been delivered, according to the Pentagon.

Israel’s military has some of the most advanced air defense systems in the world in its arsenal. Here’s how the U.S.-deployed Thaad will bolster it even further.