Saudi Arabia and its allies launched a diplomatic boycott of Qatar and closed their frontiers last year, accusing the gas-rich emirate of cosying up to Iran and sponsoring Islamist groups.

US President Donald Trump, fresh from a successful trip to Riyadh, seemed at first to take the Saudi side in the dispute and demanded that Qatar, which denies the charges, change its behavior.

But US Secretary of State Rex Tillerson and Defense Secretary Jim Mattis have been working to bring the dispute to an end and bind both Qatar and its opponents into a deeper mutual alliance.

On Tuesday, these diplomatic efforts produced the first of what may become an annual US-Qatari Strategic Dialogue, hosted by Tillerson and Mattis for their counterparts from Qatar.

In opening remarks, neither side criticized Saudi Arabia or its ambitious crown prince Mohammed Bin Salman by name, but both sides stressed the importance of unity in the Gulf Cooperation Council.

"As the Gulf dispute nears the eight-month mark the United States remains as concerned today as we were at its outset," Tillerson said, opening the meeting of senior US and Qatari officials.

"This dispute has had direct negative consequences economically and militarily for those involved as well as the United States."

Saudi Arabia is also a long-time ally of the United States and is bigger, richer and more influential than Qatar, which lies on a peninsula off its neighbor's Gulf coast in gas-rich waters.

But Qatar has parlayed its riches into an outsize influence with key economic investments in Western countries underpinning ties and winning prizes like hosting rights for the 2022 World Cup.

It has also annoyed its neighbors by funding and hosting the Al-Jazeera satellite network, which broadcasts Arabic news and views across the region that make some governments uncomfortable.

And it has fostered ties with some Islamist groups, giving it a role in regional crises that is unwelcome to some leaders.

Sometimes this is helpful to the United States: The Taliban has an office in Qatar, which serves as a back-channel for the US to get messages to their Afghan foe even as their troops fight.

But Qatar's ties to groups like the Palestinian movement Hamas, who the United States views as terrorists, have hurt ties.

Nevertheless, Qatar is also host to the huge Al-Udeid air base, a hub for allied aircraft in many Middle East conflict and home to thousands of US personnel and a forward command center.

Tillerson and Mattis both praised Qatar's improved cooperation in counterterrorism and praised the military relationship, while expressing the hope that the spat with Saudi would end.