US President Donald Trump has given Tehran two months to reach a new nuclear agreement before he launches military action against Iran's nuclear facilities, according to a letter he sent to Iranian Supreme Leader Ali Khamenei.

Axios reported on Wednesday, citing informed sources, that "Trump's letter to Iranian Supreme Leader Ali Khamenei included a two-month deadline to reach a new nuclear agreement."

According to the website, "It is not yet clear whether the countdown to the deadline begins from the time the letter is delivered or from the moment negotiations begin, but Iran's rejection of Trump's initiative and refusal to enter into negotiations could increase the likelihood of "American or Israeli military action against Iranian nuclear facilities."

Two weeks ago, Trump said in an interview with Fox News that he had sent a letter to Iran's Supreme Leader proposing "direct negotiations."

The next day, he said the United States was "in its final moments with Iran," adding, "They cannot be allowed to possess a nuclear weapon. Something will happen soon." He emphasized, "I would prefer a peace agreement, but the other option will solve the problem."