US Defense Secretary Visits Key Ally Qatar

US Defence Secretary Jim Mattis met Qatar's emir on Saturday during a visit to the oil-rich Gulf state, home to the largest US air base in the Middle East.

The visit to Doha is part of a regional tour that has included stops in Saudi Arabia, Egypt and Israel. Mattis is scheduled to visit Djibouti on Sunday.

The Pentagon chief's meeting with Emir Sheikh Tamim bin Hamad Al-Thani aimed to "reinforce relationships" between the two countries, Mattis said.

"Relationships get better or weaker, and I'm committed to making it better from our side," Mattis told the Qatari leader.

Their talks were expected to focus on the fight against the Islamic State group, the conflict in Syria and the regional role of Iran, which Mattis has described as "destabilising".

Mattis was also due to hold talks with Defence Minister Khaled al-Attiya.

Washington's relations with Gulf Arab states became increasingly frayed during the presidency of Barack Obama, whom leaders saw as too reluctant to intervene in the civil war in Syria and overly friendly with regional rival Iran.

Mattis, who commanded troops during the US-led invasion of Iraq in 2003, said in Israel on Friday that there was "no doubt" Syria has kept some chemical weapons and warned President Bashar al-Assad's regime not to use them.

Assad has said repeatedly that his forces turned over all chemical weapons stockpiles in 2013, under a deal brokered by Russia to avoid threatened US military action.

A small but strategic state in the Gulf, Qatar plays a key role in regional politics.

It is home to the Al-Udeid air base which houses around 10,000 US troops.

A longtime supporter of Syrian rebel groups, Qatar cosponsored a deal with regime ally Iran late last month that has seen the evacuation of thousands of Shiite civilians from two government-held towns in northern Syria under siege by the rebels.

A mainly Qatari hunting party, who had been kidnapped in southern Iraq in December 2015, were also freed. 

Their abduction was widely linked to Shiite militias with ties to Iran and sources in Baghdad said their release was part of the deal.

Hundreds of civilians and fighters were also evacuated from rebel-held areas near Damascus under siege by pro-government forces.