WASHINGTON, April 19 (Xinhua) -- U.S. Secretary of State Rex Tillerson said Tuesday that Iran was complying with a 2015 nuclear deal.

In a letter to House Speaker Paul Ryan, Tillerson certified that Iran was compliant through April 18 with its commitments under the 2015 Iran nuclear deal.

It was the first certification of Iran's compliance issued by the Trump administration. Like his predecessor John Kerry, Tillerson is required to send the certification every 90 days.

However, calling Iran "a leading state sponsor of terror," Tillerson informed Congress that the Trump administration had directed a full review of the 2015 nuclear deal to evaluate whether continued sanctions relief was in the U.S. national security interests.

During his campaign, Trump repeatedly criticized the Iran nuclear deal, calling it "the worst deal ever negotiated."

Iran and six world powers -- Britain, China, France, Germany, Russia and the United States -- reached an agreement on the Iranian nuclear issue in July 2015 that put it on the path of sanctions relief but with more strict limits on nuclear program.

The deal set limits on Iran's nuclear activities as it would take Tehran at least one year to produce enough fissile material for producing a nuclear weapon, and allowed regular inspections of the facilities inside Iran.

In return, the United States and the European Union will suspend nuclear-related sanctions against Iran, with the lifting of all past UN Security Council sanction resolutions.