US vice president lands in Iraq for surprise visit
Pence's unannounced landing at Ain al-Asad base - his first visit to Iraq as vice president - came nearly a year after President Donald Trump made his own surprise trip to the sprawling complex.
Trump drew criticism for the lightning-fast visit, in which he briefly met with troops but did not see any Iraqi officials.
That visit was veiled in such secrecy there was speculation that most Iraqi authorities had not been informed the president was coming.
No schedule has been announced for Pence's visit, and the US embassy in Baghdad told AFP it had no details to share on the trip.
Washington led the 2003 invasion of Iraq that toppled then-dictator Saddam Hussein, dismantled its security forces and then attempted to rebuild the country's institutions.
After years of working closely together, ties between the two countries are currently at their "coldest", US and Iraqi officials have told AFP.
Prime Minister Adel Abdel Mahdi, in office for the past year, has yet to visit Washington, and Trump has not met top officials in Baghdad.
The US currently has 5,200 troops in Iraq, part of a US-led international coalition against IS.
Their presence at several bases in Iraq has been the subject of debate, with pro-Iranian Shia militias and politicians making frequent demands for their withdrawal.
In October, US Defence Secretary Mark Esper said American troops withdrawing from Syria would stay in Iraq "temporarily" before returning to the US.
The troops have been targeted in mystery strikes on several occasions in the past few months.
Most recently, at least 17 rockets struck a military base north of the Iraqi capital where US troops are deployed, Iraqi security sourced said on November 9.
Iraqi commander of operations Noman Zobaei said forces responded to the attack in a strike that “killed three terrorists and destroyed a vehicle”. A second vehicle loaded with another missile was seized from the scene of the operation, according to local Alsumaria TV.
Comment: Tuk-tuks of Tahrir: The unlikely symbol of a revolution in Iraq
It is unknown who is responsible for the attack however similar mystery strikes also targeted the base last month, though no damage or casualties were reported.
It is unknown who is responsible for the attacks however several mystery strikes have targeted Iraq's Popular Mobilisation Forces (PMF) - a coalition of some 70, mostly Shia militias backed by Iran - in recent months.
Since mid-July, more than five PMF arms' depots and training camps have been targeted in apparent attacks.
The latest such incident took place in October when unidentified aircraft launched airstrikes on PMF bases near Syria's border.
The PMF have repeatedly blamed Israel for raids by unmanned aircraft but Iraq's prime minister accused Israel of being behind the attacks.
"Investigations into the targeting of some Popular Mobilisation Forces positions indicate that Israel carried it out," Prime Minister Adel Abdul Mahdi was quoted by Al Jazeera as saying.
A spokeswoman for the Israeli military declined to comment on the Iraqi premier's remarks.
US and Middle East intelligence officials confirmed in August that a string of unclaimed attacks against the Shia militia bases in Iraq were carried out by Israel.
Israel has repeatedly bombed Iranian targets in neighbouring Syria, but an expansion of the campaign to Iraq would risk damaging Washington's relations with Baghdad.
Israel has accused Tehran of attempting to establish a land corridor from Iran to Lebanon, via Iraq and Syria, and the strikes appear to correspondent with this alleged supply route.
Iran has a strong military and militia presence in Iraq and Syria and backs Lebanese movement Hezbollah.
The PMF was established in 2014 from mostly-Shia armed groups and volunteers to fight the Islamic State group and is now formally part of Iraq's armed forces.
But the US and Israel fear some units are an extension of their arch-foe Iran and have been equipped with precision-guided missiles that could reach Israel.