U.S. President Donald Trump says "Iran appears to be standing down" and no American was killed in Iran's missile attacks on military bases in Iraq hosting U.S. forces.

President Trump spoke on Wednesday flagged by Vice President Mike Pence and top military officials.

"As long as I am President of the United States, Iran will never be allowed to have a nuclear weapon…I am pleased to inform you the American people should be extremely grateful and happy. No Americans were harmed in last night's attack by the Iranian regime. We suffered no casualties. All of our soldiers are safe and only minimal damage was sustained at our military bases," he said.

Trump also promised to impose new economic sanctions on Iran following the attacks.

"As we continue to evaluate options in response to Iranian aggression, the United States will immediately impose additional punishing economic sanctions on the Iranian regime. These powerful sanctions will remain until Iran changes its behavior," President Trump said.

The U.S. President also called for collaboration in the fight against ISIS, which he termed a natural enemy.