Donald Trump’s first option in dealing with Tehran is diplomacy, but he is willing to use lethal force if necessary, the White House said Tuesday as his top diplomat prepared to brief congressional leaders on Iran.

“President Trump’s first option is always diplomacy. But as he has shown, he is willing to use the lethal force of the United States military if necessary,” press secretary Karoline Leavitt told reporters at the White House. “The president is always the final decision maker around here.”

Marco Rubio, the U.S. secretary of state, was scheduled to brief top congressional leaders known as the Gang of Eight later Tuesday, according to the U.S. Department of State. Rubio is expected to update lawmakers on Iran, a source familiar with the matter said.

The United States has deployed a significant naval presence near Iran’s coast amid the possibility of military strikes against the Islamic Republic.

Trump said on Feb. 19 that he was giving Tehran roughly 10 to 15 days to reach a deal.

The president could also address his threat of strikes over Iran’s nuclear program during his State of the Union speech Tuesday night.