An executive order said the United States faced a “catastrophic threat” from advanced aerial weapons. But a defense system like Israel’s may not be feasible in the country, which is more than 400 times larger.

President Trump signed an executive order to build an "Iron Dome for America," modeled on Israel’s missile defense system.

President Trump on Monday night signed an executive order to create a next-generation missile defense shield, which the White House referred to as the “Iron Dome for America” after Israel’s