The Lebanese Health Ministry announced that 50 people have been killed and over 300 have been injured in Israeli strikes since Monday.

The U.S. embassy in Amman, Jordan, announced it is canceling appointments until further notice and has instructed personnel to shelter-in-place.

"The embassy has instructed all Mission personnel to shelter-in-place. We recommend all Americans do the same," the alert on Wednesday said.

Canadian Prime Minister Mark Carney told reporters the U.S. and Israel's actions in Iran may be "inconsistent with international law."

"It's for the United States and Israel to make the case, and whether or not that is the case," he said. "It is for others more expert than me -- I'm not a lawyer, certainly not an international lawyer -- who are more expert to make that determination."

Carney said Canada regrettably supports efforts to prevent Iran from obtaining a nuclear weapon "because the current conflict is another example of the failure of the international order."

"Despite decades of United Nations Security Council resolutions, the tireless work of the International Atomic Energy Agency, and a succession of sanctions and diplomatic frameworks, Iran’s nuclear threat remains," Carney said. "And now the United States and Israel have acted without engaging the United Nations or consulting with allies, including Canada."

Carney called for a "rapid de-escalation of hostilities."

"Resolution of this crisis requires commitment to a broader political solution," he said. "Diplomatic engagement is essential to avoid a wider and deeper conflict."

The Al Udeid Air Base -- the largest US military base in the Middle East -- was struck by a ballistic missile from Iran, the Qatari Ministry of Defense said early Wednesday local time.

No one was injured, it said.

A second ballistic missile launched from Iran was intercepted, the defense ministry said.

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