As Iran retaliates, largest US military base in Middle East hit by ballistic missile, Qatar says

Senate Minority Leader Chuck Schumer said the classified briefing on Iran between Trump administration officials and members of the Gang of 8 "raised more questions than it answered."

"Look, a whole lot of questions were asked," Schumer told reporters Monday following the briefing on Capitol Hill. "I found their answers completely and totally insufficient. In fact, at least to me, that briefing raised many more questions than it answered."

House Speaker Mike Johnson, meanwhile, said he was "very satisfied" with the closed-door briefing after hearing from CIA Director John Ratcliffe, Chairman of the Joint Chiefs of Staff Gen. Dan Caine, Defense Secretary Pete Hegseth and Secretary of State Marco Rubio.

Johnson called the attack on Iran a "defensive operation" -- echoing Rubio's reasoning that an Israeli operation was already in motion -- and that the administration "had a very difficult decision to make."

"The first responsibility of the federal government is to protect the country and its interests, and that's what we did here," Johnson said.

-ABC News' Lauren Peller, John Parkinson, Hannah Demissie and Jay O'Brien

Six U.S. service members have been killed since the operation against Iran began, according to U.S. Central Command.

"U.S. forces recently recovered the remains of two previously unaccounted for service members from a facility that was struck during Iran's initial attacks in the region," CENTCOM said in a statement Monday. "Major combat operations continue."

All six deaths occurred from a single incident in Kuwait, sources told ABC News.

The names of the fallen troops will be withheld until 24 hours after next of kin notification, CENTCOM said.

An Islamic Revolutionary Guard Corps commander said the Strait of Hormuz is "closed."

"The strait is closed, and whoever wants to cross, our heroes in the navy of the IRGC and army will set those ships on fire," Brigadier General Ebrahim Jabari said on Iranian state TV earlier.

The Strait of Hormuz is one world's most important chokepoints for oil. Roughly 20% of the world’s oil passes through the Strait, according to the U.S. Energy Information Administration.

The Israel Defense Forces said the Israeli Air Force has "struck and dismantled" the Iranian state broadcaster "a short while ago."

"The center was also recently used by the Iranian regime's forces to advance military activities under the guise of civilian activity and assets, in addition to the propaganda activities that emanate from the communications center," the IDF said in a statement.

"The IDF will continue to strike the Iranian regime's infrastructure across Tehran," the statement added.