The United States agreed a major warplane sale to Qatar and began manoeuvres with the emirate's navy Thursday, underscoring its commitment to their military alliance despite Doha's rift with other Gulf allies.
Washington has sent conflicting signals to its longtime ally about its position on the diplomatic crisis which has seen Saudi Arabia and its allies impose sweeping sanctions on the emirate.
Last week, US President Donald Trump expressed support for the Saudi-led allegations against Qatar, charging that it had "historically been a funder of terrorism at a very high level".
But Pentagon and State Department officials have since scrambled to reassure the emirate, which houses the largest US airbase in the Middle East and the command headquarters for US military operations in Iraq, Syria and Afghanistan.
US Defence Secretary Jim Mattis welcomed his Qatari counterpart Khalid al-Attiyah to Washington on Wednesday for the signing of the agreement for the sale of F-15 fighters.
"The $12-billion sale will give Qatar a state-of-the-art capability and increase security cooperation and interoperability between the United States and Qatar," the Pentagon said.
It did not provide additional details on the sale but Bloomberg reported it could involve as many as 36 warplanes.
The Pentagon meanwhile deployed two warships to carry out joint manoeuvres with the Qatari navy in the Gulf.
The vessels docked in Hamad Port, south of the capital Doha, on Wednesday, the Qatari defence ministry said.
Mattis and Attiyah also discussed the US-led military campaign against the Islamic State group and "the importance of de-escalating tensions so all partners in the Gulf region can focus on next steps in meeting common goals".
Washington has voiced growing concern about the impact of the diplomatic crisis on its military operations against IS, just as they come to a climax in the jihadists' Iraq and Syria bastions, Mosul and Raqa.
Secretary of State Rex Tillerson said last week that the rift was "hindering" the campaign and urged Saudi Arabia and its allies to ease their "blockade".
At a Washington news conference with Tillerson on Wednesday, Saudi Foreign Minister Adel al-Jubeir denied the sanctions amounted to a blockade, insisting that it was the kingdom's sovereign right to close its airspace to Qatari aircraft and seal the emirate's sole land border.
Saudi Arabia and its allies -- led by the United Arab Emirates, Egypt and Bahrain -- have said there can be no mending of ties until Qatar ends its support for groups like the Muslim Brotherhood, which the four governments blacklist as a "terrorist" group.
But Qatar and its allies -- led by Turkey -- say the emirate has every right to conduct an independent foreign policy and have branded the sanctions imposed as "inhumane and un-Islamic".
Turkey has launched a diplomatic push to try to resolve the crisis on behalf of its ally, throwing its support behind a UN-backed mediation effort by Kuwait, one of the Gulf states which did not join the Saudi-led sanctions.
Foreign Minister Mevlut Cavusoglu was in Kuwait on Thursday after talks in Qatar on Wednesday. He is due to fly on to Saudi Arabia on Friday.
Turkey has been caught in a delicate balancing act. While standing squarely behind its ally, it has been anxious not to antagonise key regional power Saudi Arabia.
"Saudi Arabia has the potential and capability to solve this crisis as a wise state and big brother of the region and also as a major actor," Turkey's presidential spokesman Ibrahim Kalin said on Wednesday.
The United Nations has expressed mounting concern about the humanitarian impact of the crisis.
As well as severing economic and political ties, the four governments ordered Qataris out within 14 days and called home their own citizens.
Bahrain and the UAE have also banned expressions of sympathy for Qatar.
Bahrain announced on Wednesday that it had detained a citizen for sympathising with Qatar on social media.
"I am alarmed about the possible impact on many people's human rights," UN human rights chief Zeid Ra'ad Al Hussein said on Wednesday.
"It is becoming clear that the measures being adopted are overly broad in scope and implementation," he added.