The president campaigned on a vow to bring American troops home, but his standoff with Iran has seen thousands more soldiers deployed to the Middle East.
Special Representative for Iran Brian Hook said Tehran was responsible for 17 percent of all U.S. service personnel deaths between 2003 and 2011.
Reuters reported that Tehran was supplying missiles to Shiite Muslim militias in Iraq just a day after an Israeli satellite imagery firm alleged Iranian support for missile sites in Syria.
The U.S. secretly backed both Iran and Iraq in their 1980s war. Their current alliance now spells trouble for American policy in the Middle East.
Despite recent rifts in their strategic relationship, Russia and Iran are still working together in what appears to be the latter stages of Syria's civil war.
Around 2,000 members of the Afghan Ulema Council were meeting in Kabul when a lone bomber struck.
President Donald Trump called for Arab partners to contribute more to the fight against ISIS in Syria, but Saudi backing could further complicate the war.
Having reached out for potential investment with South Korea, Saudi Arabia is talking tough against Iran's "Hitler."
Groups the U.S. is considering labeling terrorist organizations have officially become part of the Iraqi military that Washington sponsors.
Iran's supreme leader Ayatollah Ali Khamenei said, "what the Saudis do...is certainly a betrayal of the Islamic Ummah and the Muslim World."
Some view the Islamic Military Coalition as essentially a Sunni alliance against Iran.
Bahrain said the "terrorist act" by Iran was meant to destabilize the mostly Shiite Muslim kingdom ruled by a Sunni Muslim monarchy.
More than 1,700 civilians have been killed in attacks in Afghanistan this year.
Saudi Arabia reopened its embassy in Baghdad in 2015 following a 25-year break.
Human Rights Watch said an Iraqi unit trained by American forces summarily executed prisoners in western Mosul.
Qatar has become a proxy fight between Iran and Saudi Arabia, with the U.S. on the sidelines.
Are the U.S. Navy as relaxed about repression in Bahrain as the White House appears to be?
He could also end the house arrest of two former presidential candidates.
The U.S. approved $295.6 million in military assistance for Kurdish peshmerga units in Iraq as they prepare for a joint anti-ISIS offensive with allied Shiite Muslim militias.