Republican US Senator Lindsey Graham said on Tuesday that top administration officials told senators in a briefing that the recent attacks on ships and a pipeline in the Middle East were directed by Iran's government and ayatollah.

“They explained to us how the Iranian threat streams were different than in the past, that the attack on the ships and the pipeline was coordinated and directed by the Iranian government, the ayatollah,” Graham told reporters.

Senior officials from the Trump administration held a closed-door briefing for the US Senate and House of Representatives about Iran on Tuesday. The briefers were Secretary of State Mike Pompeo, Acting Secretary of Defense Patrick Shanahan, Joint Chiefs of Staff Chairman General Joseph Dunford and an unnamed representative of the intelligence community, Congressional aides said.

Shanahan said on Tuesday after briefing lawmakers on the threat from Iran that the United States had deterred possible attacks by deploying forces to the region.

"We have deterred attacks based on our reposturing of assets and deterred attacks against American forces. Our biggest focus at this point is to prevent Iranian miscalculation," Shanahan told reporters on Capitol Hill.