After alerts were activated across Israel early Tuesday local time, the Israel Defense Forces said "launches from Iran have been identified toward several areas in the country's territory."

The United Arab Emirates' Ministry of Defense said in a recent statement that its "air defenses are currently dealing with a barrage of ballistic missiles coming from Iran."

The Qatari Ministry of Defense said it "successfully continued to intercept and neutralize two ballistic missiles that targeted several areas within the country."

In Kuwait, "armed forces are currently dealing with a wave of missiles and drones that have been detected in the airspace," army officials said.

Emergency sirens have also gone off in Bahrain, according to the country's interior ministry. "Citizens and residents are urged to remain calm and head to the nearest safe place," the ministry said.

Iranian Foreign Minister Abbas Araghchi said he believes American bases are "legitimate targets" in a new interview with Iranian state TV.

"When the United States attacks us -- whether by fighter jets or the ships it deploys -- they have access to our territory to strike with all kinds of missiles and aircraft. We cannot reach their territory, but we can reach their bases. I think those bases are legitimate targets," Araghchi said.

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.