Iran has responded to a letter sent by U.S. President Donald Trump to its supreme leader in an attempt to jump-start talks over Tehran’s rapidly advancing nuclear program.

Iranian President Masoud Pezeshkian said the Islamic Republic rejected direct negotiations with the United States over its rapidly advancing nuclear program. NBC News’ Daniele Hamamdjian reports.

Iranian President Masoud Pezeshkian reiterated Sunday that his country had rejected holding direct talks with the Trump administration over its nuclear program but is willing to begin indirect talks.

Iran and Russia took decisively different approaches in response to President Donald Trump's threats as Tehran vowed action against any "mischief" while the Kremlin remains tight-lipped.

The Iranian leader, however, warned of retaliatory attacks against the U.S. and Israel if President Donald Trump follows through with the threat to bomb his country.

Iran's Supreme Leader Ayatollah Ali Khamenei said on Monday the U.S. would receive a strong blow if it acts on Trump's threat to bomb unless Tehran reaches a new nuclear deal.