Forty years after President Ronald Reagan first conceived the idea, defense industry leaders say the technology is finally advanced enough to build an invisible protective dome of space-based radars, missile interceptors and laser weapons over the United States. President Donald Trump, infatuated by the Iron Dome missile defense system over Israel, first ordered the Defense Department to begin drawing up plans for a U.S. version, the “Golden Dome,”...

The Pentagon said it would investigate what it claims are leaks of national security information, saying that the probes could include polygraph tests for employees in the Defense Department. Defense Secretary Pete Hegseth’s chief of staff, Joe Kasper, sent a memo Friday saying that the Pentagon’s intelligence and law enforcement arms are probing “recent unauthorized disclosures” of national security information, without offering details about alleged leaks. “Recent unauthorized...