'It is a last-ditch effort': Rex Tillerson looks to defuse Qatar crisis on Gulf tour

US Secretary of State Rex Tillerson arrives Monday in Kuwait, the key mediator between Qatar and its Arab neighbours, for talks aimed at defusing the Gulf's worst crisis in years.

Tillerson will shuttle between Kuwait, Qatar, Saudi Arabia from Monday to Thursday in what is the first serious intervention by Washington in the Gulf crisis.

The dispute has seen a Saudi-led alliance impose sanctions on Doha over its alleged ties to both Islamist extremist groups and Shiite-dominated Iran.

As they met in Egypt last week, Saudi Arabia and its allies said they planned to tighten sanctions against the gas-rich emirate, after Qatar refused to comply with a list of demands.

A spokesman for Tillerson said ahead of his landing in Kuwait that it remained to be seen "if there's even a possibility of some outcomes" towards resolving the crisis.

"Right now, after Egypt, we're months away from what we think would be an actual resolution and that's very discouraging," RC Hammond told reporters.

On June 5, Saudi Arabia, the United Arab Emirates, Bahrain and Egypt abruptly severed diplomatic ties with Qatar, suspending transport links with Doha and ordering all Qataris to repatriate within 14 days.

The four nations later issued a list of 13 demands to be met to lift the sanctions, including that Qatar shut down broadcaster Al-Jazeera, close a Turkish military base and downgrade diplomatic ties with Iran.

Qatar refused to meet the demands last week on the grounds they undermined its national sovereignty. It has also categorically denied having any ties to extremist groups.

Tillerson, the former chief executive of energy giant Exxon Mobil, arrives in the Gulf after a stop in Istanbul, where he discussed the Syria war to a failed 2016 coup in Turkey.

- 'Last-ditch effort' -

Analysts say Tillerson's success in the Gulf may be contingent on his ability to maneuver regional skepticism over conflicting stances from Washington on the crisis.

US President Donald Trump initially supported longtime US ally Saudi Arabia, but his stance was later contradicted when the US Department of State took a more neutral position.

Tillerson's impact largely depends on whether regional officials "believe that the secretary of state is fully backed by President Trump", London-based political analyst Neil Partrick said.

"If Tillerson can convincingly frame his mission as delivering a deal for the United States that is all about defeating terrorism... then he may have some chance," said Partrick, who focuses on Gulf politics.

But despite strong mediation efforts by Kuwait and others, governments across the region say they may remain deadlocked for the foreseeable future.

"No diplomatic effort or... mediation will succeed without Doha being rational, mature and realistic," UAE state minister for foreign affairs Anwar Gargash tweeted last week.

Tillerson's visit comes on the heels of a string of official visits to the region, including UN diplomats and the foreign ministers of Britain, Germany and Oman.

UK National Security Advisor Mark Sidwell is scheduled to attend part of the meeting between Tillerson and Kuwait's Foreign Minister Sheikh Sabah Khaled Al-Sabah.

Despite the deadlock, regional experts say Washington's interest in finding a solution to the crisis is a welcome step.

"The tour comes after contradictory statements from Washington over the dispute," said analyst Abdullah al-Shayeji Shayeji, a political science professor at Kuwait University.

"It is a last-ditch effort to rescue the situation and try to resolve the crisis, which is impacting regional stability, the war on terror and the campaign against the Islamic State" jihadist group, Shayeji said.

He said mutual concessions from the feuding states would however be necessary.

The United States and its Western allies have vast economic and political interests in the Gulf, which pumps one fifth of the world's oil supplies, houses one third of proven global crude reserves and sits on one fifth of the world's natural gas deposits.