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.

Israeli Prime Minister Benjamin Netanyahu said Israeli forces were "striking the heart of Tehran with increasing strength, which will increase even more in the coming days."

Netanyahu's comments were part of a recorded video message in which said he had "given instructions for the continuation of the campaign" after meeting with senior Israeli officials, including "the minister of defense, the chief of staff and the head of the Mossad," Israel's national intelligence agency.

Netanyahu also said the joint U.S.-Israeli attacks had "eliminated dozens of senior officials of the oppressive regime" in addition to "the dictator Khamenei," referring to Iran's late Supreme Leader Ayatollah Ali Khamenei, who was killed in Saturday's attacks.

He also addressed reports of Israelis killed and injured in retaliatory strikes on Israel, saying "These are painful days. ... My heart goes out to the families."

"We are in a campaign in which we are bringing the entire strength of the IDF, as never before, to this campaign to ensure our existence and our future," Netanyahu said. "But we are also bringing to this campaign the assistance of the United States, my friend, the President of the United States, Donald Trump, the U.S. military. This combination of forces allows us to do what I have been hoping to do for 40 years: to strike the terrorist regime squarely in the face. I promised, and so we will."

-ABC News' Victoria Beaule