Iran complained to the United Nations Security Council on Monday over US President Donald Trump’s threats against the Islamic Republic.

In a letter seen by the Reuters news agency, Iran's UN Ambassador Amir Saeid Iravani described Trump’s threats as "reckless and belligerent" and "a flagrant violation of international law".

The Iranian envoy wrote in the letter that Tehran "strongly warns against any military adventurism and will respond swiftly and decisively to any act of aggression or attack by the United States or its proxy, the Israeli regime, against its sovereignty, territorial integrity, or national interests."

The complaint comes a day after Trump warned Iran that "if they don't make a deal, there will be bombing — and it will be bombing the likes of which they have never seen before."

In response, Iran’s state-controlled Iranian newspaper Tehran Times wrote in a post on X that Iran's missiles are "loaded onto launchers in all underground missile cities and are ready for launch."

Later, Trump again threatened Iran, saying he could consider imposing secondary tariffs on Iran should the Islamic Republic fail to agree to a deal on its nuclear program.

On Monday, Iranian Supreme Leader Ayatollah Ali Khamenei warned Trump against any attack on Iran, saying that if the US follows through on its threats, it will receive a "strong blow."

Later, Khamenei’s advisor Ali Larijani warned that Iran would be forced to develop a nuclear bomb if the US or Israel attack the Islamic Republic.