"Iran's key nuclear enrichment facilities have been completely and totally obliterated. Iran, the bully of the Middle East, must now make peace," Trump said in a televised address to the nation from the White House after the strikes.

Here is a roundup of the key reactions:

- Iran: 'Everlasting consequences' -

Iran's Foreign Minister Abbas Araghchi condemned the US attacks as "outrageous" and said his country has a right to defend its sovereignty.

"The events this morning are outrageous and will have everlasting consequences," he posted on X, adding that the attacks were "lawless and criminal" behavior.

"In accordance with the UN Charter and its provisions allowing a legitimate response in self-defense, Iran reserves all options to defend its sovereignty, interest, and people," the foreign minister said.

Iran's atomic energy organization also called the US attacks "a barbaric act that violates international law."

The agency added that it "will not let the path of development of this national industry... be stopped."

- Israel: 'Change history' -

Israeli Prime Minister Benjamin Netanyahu congratulated Trump, saying the attacks will "help lead the Middle East and beyond to a future of prosperity and peace."

"Your bold decision to target Iran's nuclear facilities with the awesome and righteous might of the United States will change history," Netanyahu said in a video message, adding that the attacks demonstrated "America has been truly unsurpassed."

He also told Israelis that his promise to destroy Iran's nuclear facilities had been "fulfilled."

- UK: 'Stability is priority' -

UK Prime Minister Keir Starmer called on Iran to "return to the negotiating table and reach a diplomatic solution to end this crisis."

"Iran can never be allowed to develop a nuclear weapon and the US has taken action to alleviate that threat," Starmer said on X, adding that "stability in the region is a priority."

- EU: 'Step back' -

The European Union's top diplomat Kaja Kallas called for de-escalation and a return to negotiations.

"I urge all sides to step back, return to the negotiating table and prevent further escalation," Kallas wrote on X, adding Iran must not be allowed to develop a nuclear weapon and that EU foreign ministers will discuss the situation on Monday.

- UN: 'Dangerous escalation' -

UN Secretary-General Antonio Guterres called the strikes a "dangerous escalation in a region already on the edge."

"At this perilous hour, it is critical to avoid a spiral of chaos," Guterres said in a statement. "There is no military solution. The only path forward is diplomacy. The only hope is peace."

The UN's nuclear agency also reported that it had not detected any increase in "off-site radiation levels" after the attacks on the three nuclear sites in Iran.

The agency's chief called for an emergency meeting Monday.

- Iraq: 'Grave threat' -

Iraq warned that the US attacks on its neighbour Iran's nuclear facilities threaten peace and stability in the Middle East.

"This military escalation constitutes a grave threat to peace and security in the Middle East and poses serious risks to regional stability," said government spokesperson Basim Alawadi.

- Saudi Arabia: 'Exercise restraint' -

Saudi Arabia expressed "great concern" after the US air strikes on nuclear facilities in its neighbour, the "sisterly Islamic Republic of Iran."

"The Kingdom underscores the need to exert all possible efforts to exercise restraint, de-escalate tensions, and avoid further escalation," the Saudi foreign ministry posted on X.

- Hamas: 'Brutal aggression' -

Palestinian militant group Hamas condemned the "blatant US aggression against the territory and sovereignty of the Islamic Republic of Iran."

"This brutal aggression is a dangerous escalation," Hamas said, calling the attack "a flagrant violation of international law, and a direct threat to international peace and security."

- Democrats: 'Unilateral military action' -

The top Democrat in the US House of Representatives accused Trump of pushing the United States toward war.

"President Trump misled the country about his intentions, failed to seek congressional authorization for the use of military force and risks American entanglement in a potentially disastrous war in the Middle East," Congressman Hakeem Jeffries said in a statement.

"Donald Trump shoulders complete and total responsibility for any adverse consequences that flow from his unilateral military action."