Defense Secretary Pete Hegseth said early Monday the U.S. military operation in Iran is  "laser-focused" as the U.S. and Israeli military operation against Iran continued into a third day.   "Destroy Iranian missiles, destroy Iranian missile production, destroy their navy and other security infrastructure and they will never have nuclear weapons," said Hesgeth, who was joined by Joint Chiefs of Staff Gen. Dan Caine.  The Pentagon announced Monday that a fourth American service member has been