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 Donald Trump has ordered the development of an "Iron Dome" defense system to shield the United States from an intercontinental missile attack.

When it comes to protecting U.S. territory from missiles fired by such nuclear-powered countries as Russia, China, and North Korea (which is Trump’s goal in ordering this project), something like Iron Dome would have no capability whatsoever; and