Iran's ambassador to the United Nations, Amir Saeid Iravani, condemned the United States' attacks on Iran during a meeting with the UN Security Council.

Iravani said the strikes on Iran's nuclear sites used the Non-Proliferation Treaty (NPT) as a "political weapon," calling it "aggression and unlawful action."

The ambassador warned that Iran's response would be determined by its armed forces. Iravani also denounced the assassination of Iran's General Qasem Soleimani.

"The timing, nature and the scale of Iran's proportionate response will be decided by its armed forces," Iravani said, adding, "All U.S. allegations against Iran are unfounded, with no legal basis and politically motivated."

-ABC News' Will Gretsky

President Donald Trump said in a new post to Truth Social on Sunday that the pilots of the B-2 bombers that participated in strikes on Iranian nuclear facilities have returned to U.S. soil.

"The GREAT B-2 pilots have just landed, safely, in Missouri. Thank you for a job well done!!!," Trump wrote.

More than 125 aircraft participated in the mission, including seven B-2 Spirit stealth bombers, which were launched from the continental U.S. and refueled multiple times in midair as they flew 18 hours to reach their targets, according to Gen. Dan Caine, chairman of the Joint Chiefs of Staff.

Other aircraft that participated in the mission included B-2 bombers used as decoys, as well as refueling tankers, fighter escorts, and drones that provided Intelligence, surveillance and target acquisition, according to U.S. officials.

-ABC News' Michelle Stoddart

The leaders of France, the United Kingdom and Germany released a joint statement on Sunday following the United States' strikes on Iran.

"We reiterate our commitment to peace and stability for all countries in the region," the statement posted to French President Emmanuel Macron's official website said.

"We affirm our support for Israel's security," the leaders continued, saying, "We have always been clear that Iran can never have a nuclear weapon and can never again pose a threat to regional security."

Macron, along withthe UK's Prime Minister Keir Starmer and German Chancellor Friedrich Merz called on Iran to "engage in negotiations leading to an agreement that addresses all concerns related to its nuclear program."

"We urge Iran to refrain from further actions that could destabilize the region," the leaders added.

President Donald Trump appeared to float the idea that there should be a change in leadership in Iran in a new social media post on Sunday. Trump said that though it is "not politically correct" to discuss a regime change, he criticized the current leadership in Iran and also asked, "Why wouldn’t there be a Regime change???"

"It’s not politically correct to use the term, “Regime Change,” but if the current Iranian Regime is unable to MAKE IRAN GREAT AGAIN, why wouldn’t there be a Regime change???," Trump wrote in the brief post on his social media platform, Truth Social.

"MIGA!!!," Trump added in the post, a twist on the MAGA term that he coined.

In an earlier post on Sunday, Trump touted the success of the U.S. strikes on Iranian nuclear sites.

"The damage to the Nuclear sites in Iran is said to be 'monumental.' The hits were hard and accurate," Trump wrote.

-ABC News' Michelle Stoddart