President Donald Trump on Sunday posted a video acknowledging for the first time on camera the death of three U.S. troops killed during the U.S. operation against Iran over the weekend.

The president said he was sending “our immense love and eternal gratitude to the families of the fallen” before warning that more U.S. troops will “likely” be killed as the operation rages on.

“Earlier today, CENTCOM shared the news that three U.S. military service members have been killed in action. As one nation, we grieve for the true American patriots who have made the ultimate sacrifice for our nation, even as we continue the righteous mission for which they gave their lives, we pray for the full recovery of the wounded and send our immense love and eternal gratitude to the families of the fallen,” Trump said.

“And sadly, there will likely be more before it ends. That's the way it is -- likely be more, but we'll do everything possible. But that won't be the case. But America will avenge their deaths and deliver the most punishing blow to the terrorists who have waged war against, basically, civilization,” Trump added.

Trump started the speech by touting the nine Iranian naval vessels he said were sunk, and said, for the first time on camera, that the Ayatollah was dead. The president also said that “the entire military command is gone” in Iran.

Later in the speech, Trump warned that those who did not surrender would face “certain death.”

-ABC News' Meghan Mistry, Nicholas Kerr, Fritz Farrow and Selina Wang

U.S. lawmakers in the House and Senate will receive classified briefings on Tuesday from Trump administration officials on the military operation in Iran, multiple sources told ABC News.

Senators are scheduled to be briefed at 3:30 p.m. ET on Tuesday. A briefing for House members will follow at around 5 p.m., according to the sources

The briefers from the administration are expected to include Secretary of State Marco Rubio, Joint Chiefs Chairman Gen. Dan Caine, CIA Director John Ratcliffe, and Secretary of Defense Pete Hegseth, according to the sources.

-ABC News' Jay O'Brien and Lauren Peller

The U.S. Central Command (CENTCOM) released an infographic Sunday detailing the aircraft, missiles and weapons systems used during the first 24 hours of Operation Epic Fury in Iran.

According to the infographic, the U.S. alone struck more than 1,000 targets, and that the attacks were launched at 1:15 a.m.

The list of targets hit includes command and control centers, Islamic Revolutionary Guard Corps (IRGC) Joint Headquarters, IRGC Aerospace Forces HQ, missile defense sites, ballistic missile sites, Iranian Navy ships and submarines, anti-ship missile sites, and military communications facilities.

The infographic also lists the assets deployed in the attacks, including bombers and fighter jets, interceptor and anti-ballistic missile systems, aircraft carriers and guided missile destroyers, cargo and support assets and more.

-ABC News' Luis Martinez

The United Arab Emirates Ministry of Foreign Affairs announced on Sunday that it is closing its embassy in Tehran and withdrawing its ambassador to Iran.

The Ministry of Foreign Affairs also said in the same statement that it is withdrawing all members of its diplomatic mission in Iran.

The decision was made "in response to the blatant Iranian missile attacks that targeted the UAE's territory," the statement reads, in part.

"These hostile attacks against civilian sites, including residential areas, airports, ports, and service facilities, endangered innocent civilians in a serious and irresponsible escalation and constitute a flagrant violation of national sovereignty, as well as a clear breach of international law and the Charter of the United Nations," the statement further said.

-ABC News' Somayeh Malekian

A fourth U.S. service member has been killed in action, CENTCOM said.

The fourth person, who was “seriously wounded” in the initial attacks this weekend, later died from their injuries, CENTCOM said.