Israeli Prime Minister Benjamin Netanyahu congratulated US President Donald Trump on his"bold decision" to bomb three nuclear facilities in Iran, adding:"President Trump and I often say, 'Peace comes through strength.'"

In a video posted on his X account, the Israeli leader wrote that"first comes strength, then peace (...) And tonight, @realDonaldTrump and the United States acted with great force."

President Trump said in a White House address that the United States had successfully completed a strike against Iran's nuclear facilities, the first U.S. strikes in the ongoing conflict between Israel and Iran.

The strikes are a dangerous decision for the United States, as Iran has vowed to retaliate if it joins the Israeli attack, and for Trump personally, after winning the White House on a promise to keep the United States out of costly foreign conflicts and mocking the value of American interventionism.

UN Secretary-General Antonio Guterres said he was"gravely alarmed" by the "dangerous escalation" of US attacks.

"There is a growing risk that this conflict could quickly spiral out of control, with catastrophic consequences for civilians, the region, and the world," he said in a statement.

Israel's military said Saturday it was preparing for the possibility of a protracted war, while Iran's foreign minister warned ahead of the U.S. attack that U.S. military involvement"would be very, very dangerous for everyone."

The prospect of a wider war also loomed. Iran-backed Houthi rebels in Yemen indicated they would resume attacks on U.S. ships in the Red Sea if the Trump administration joined Israel's military campaign. The Houthis paused such attacks in May under an agreement with the United States.