The Trump administration said on Tuesday it was launching an inter-agency review of whether the lifting of sanctions against Iran was in the United States' national security interests, while acknowledging that Tehran was complying with a deal to rein in its nuclear program.

In a letter to U.S. House of Representatives Speaker Paul Ryan, the top Republican in Congress, on Tuesday U.S. Secretary of State Rex Tillerson said Iran remained compliant with the 2015 deal, but said there were concerns about its role as a state sponsor of terrorism.

Under the deal, the State Department must notify Congress every 90 days on Iran's compliance under the so-called Joint Comprehensive Plan of Action (JCPOA). It is the first such notification under U.S. President Donald Trump.