US Secretary of Defence Jim Mattis discussed with Sultan Qaboos of Oman a number of issues, including the rift between some Arab countries and Qatar and the ongoing war in Yemen.
Mr Mattis, who arrived in Afghanistan on Tuesday after official visits to Muscat and Manama, also addressed during talks ways to strengthen US-Omani relations.
“The defence secretary was keen to repair differences that separate the GCC countries,” said an Omani foreign ministry source, referring to the Arab countries that have cut all ties with Doha over allegations it supports extremists.
“Oman agreed to mediate with members of the GCC to solve the problems and bring back the lost unity in the regional alliance.”
Saudi Arabia, the UAE, Bahrain – GCC members – and Egypt severed ties with Qatar – also a GCC member – on June 5 last year. Oman, part of the council, has remained neutral on the issue.
The two officials also discussed the war in Yemen, where an Arab coalition is fighting against Iran-backed Houthi rebels on behalf of the internationally recognised government of President Abdrabu Mansur Hadi.
In March 2015, the member states of the GCC – with the exception of Oman – issued a joint statement that they would intervene in the Yemen war at the request of the Hadi government.
“The Sultan assured Mr Mattis that he would try and arbitrate a peaceful conclusion in Yemen to stop further bloodshed,” the source said.
Talks in Kabul
Mr Mattis arrived in Kabul on Tuesday in a surprise visit, two weeks after Afghan President Ashraf Ghani unveiled a plan to launch peace talks with the Taliban.
The insurgents have so far given no formal response to Kabul's offer for negotiations, but Mr Mattis said some insurgent leaders have expressed an interest in the discussions.
"It may not be that the whole Taliban comes over in one fell swoop, that would be a bridge too far, but there are elements of the Taliban clearly interested in talking to the Afghan government," he told reporters aboard a military jet.
Mr Ghani's peace plan includes eventually recognising the Taliban as a political party.
The insurgent group has said it is prepared to negotiate, but only with the US and not with the Kabul government, which it described last week as “illegitimate” and its peace process efforts as “deceptive”.
"Right now we want the Afghans to lead and to provide the substance of the reconciliation effort," Mr Mattis said.
Mr Ghani’s offer comes as civilian casualties have soared in recent months.
The Taliban, Afghanistan's biggest militant group, claimed 472 attacks in January alone, the Washington-based terrorism research group TRAC said.
Mr Mattis said the jump in attacks on civilians was an indication that a pressured Taliban is unable to conduct broader, ground-taking operations.
The Afghan security forces were able to stop some attacks, Mr Mattis said, though he noted he wanted to see them shift to a more "offensive mindset" in the coming months.
Mr Mattis's surprise Afghan visit, his third as Pentagon chief, was kept under tight wraps after a security incident during his last trip in September, when insurgents shelled Kabul's airport hours after he arrived.