U.S. Secretary of State Rex Tillerson, pictured in Moscow last week, says Iran has been abiding by a 2015 nuclear agreement. But he told Congress in a letter that the Trump administration was reviewing the lifting of U.S. sanctions against Iran to determine if that was in U.S. interests. Ivan Sekretarev/AP hide caption
Missiles on display in northern Tehran in 2014. A reported missile test by Iran on Sunday has led some American officials to accuse the country of violating a U.N. resolution that accompanied the 2015 nuclear deal. Atta Kenare/AFP/Getty Images hide caption
Then-Secretary of State Madeleine Albright and North Korean leader Kim Jong Il toast in Pyongyang on Oct. 24, 2000. The U.S. and North Korea signed an agreement six years earlier to curb North Korea's nuclear activities in exchange for aid, but it collapsed in 2002, during the Bush administration. Chien-Min Chung/AP hide caption
Richard Ratcliffe, second from right, delivers a petition to the British prime minister's official residence calling on Iran to release his wife, Nazanin Zaghari-Ratcliffe. She was stopped in April at the airport in Tehran with the couple's 2-year-old daughter as they tried to return to Britain after a family holiday. Ratcliffe was at the United Nations this week appealing for their release. Carl Court/Getty Images hide caption
U.S. State Department Spokesman John Kirby speaks during a briefing at the State Department on Jan. 6. Mandel Ngan/AFP/Getty Images hide caption
Secretary of State John Kerry talks with Iranian Foreign Minister Mohammad Javad Zarif in Vienna on Jan. 16, after the International Atomic Energy Agency verified that Iran met all conditions under the nuclear deal. The accord is now 1-year-old. Iran is seen as abiding by requirements of the deal, but its relations with the U.S. and other rivals have not improved on other fronts. Kevin Lamarque/AP hide caption
Chicago-based aircraft manufacturer Boeing would not divulge details about its deal with Iran Air — not the number of aircraft involved, the specific models or the price tag. Simon Dawson/Bloomberg via Getty Images hide caption
NPR's Steve Inskeep interviews President Obama at the White House about the Iran nuclear deal. Kainaz Amaria/NPR hide caption
U.S. Secretary of State John Kerry (right), along with British Foreign Secretary Philip Hammond (left), speak to reporters in London on May 12. They tried to assure European banks they won't be penalized for conducting legitimate business with Iran. Critics say it should not be up to the U.S. to encourage investment in Iran. Josh Lederman/AP hide caption
CIA Director John Brennan discussed ISIS, the FBI-Apple dispute over an iPhone, the state of the Iran nuclear deal, and his future plans as President Obama's term draws to a close. Ariel Zambelich/NPR hide caption
Director of National Intelligence James Clapper testifies Tuesday before a Senate Armed Services Committee hearing on worldwide threats. Evan Vucci/AP hide caption
Iranian shopkeepers in the main bazaar in the capital, Tehran, in September. Iranians are eager for economic sanctions to be lifted and have been moving quickly to meet their obligations under a nuclear deal, according to analysts monitoring the agreement. Atta Kenare/AFP/Getty Images hide caption
Iran's President Hassan Rouhani leaves after a televised speech in Tehran on Dec. 16. Iran has been dismantling parts of its nuclear program as required under an international deal, and some sanctions could be lifted as soon as January. Ebrahim Noroozi/AP hide caption
Iranian President Hassan Rouhani (right) meets with U.N. nuclear chief Yukiya Amano (left) and an unidentified interpreter in Tehran, Iran, last month to discuss the country's nuclear program. Vahid Salemi/AP hide caption
Ali Akbar Salehi, top, the head of Iran's Atomic Energy Organization, delivers a speech as lawmakers and officials discuss a bill on Iran's nuclear deal in parliament on Sunday. The parliament approved an outline of a bill allowing the deal's implementation. Ebrahim Noroozi/AP hide caption