US Vice President Kamala Harris on Monday led a high-level delegation to meet the United Arab Emirates' new president, who takes over after his half-brother's death, following months of strained ties between Washington and the oil-rich Gulf state.

US Secretary of State Antony Blinken arrived in Israel from Poland, where he held talks on Russia's war against neighbouring Ukraine
US Secretary of State Antony Blinken arrived in Israel from Poland, where he held talks on Russia's war against neighbouring Ukraine POOL via AFP / Jacquelyn Martin

Harris, whose team included Secretary of State Antony Blinken, Defense Secretary Lloyd Austin and CIA chief William Burns, headed the strongest delegation to visit UAE since President Joe Biden took office last year.

Sheikh Mohamed bin Zayed Al Nahyan or "MBZ", for years the de facto ruler, was chosen as president on Saturday, a day after the death of his long-ailing half-brother, former leader Sheikh Khalifa.

US Vice President Kamala Harris, pictured in Washington on May 13, 2022, at the US-ASEAN Special Summit at the State Department
US Vice President Kamala Harris, pictured in Washington on May 13, 2022, at the US-ASEAN Special Summit at the State Department AFP / OLIVIER DOULIERY

Harris said the UAE was a "friend and partner", as she congratulated Sheikh Mohamed on his election and expressed Washington's condolences.

"We are here as a delegation... to reaffirm the shared commitment we have to security and prosperity in this region, and also how the American people have benefited from this relationship in terms of security and prosperity," Harris said.

The flag of United Arab Emirates flies at half-mast outside the Sheikh Zayed Grand Mosque in Abu Dhabi on May 13, 2022, following the death of UAE's President Sheikh Khalifa bin Zayed Al-Nahyan
The flag of United Arab Emirates flies at half-mast outside the Sheikh Zayed Grand Mosque in Abu Dhabi on May 13, 2022, following the death of UAE's President Sheikh Khalifa bin Zayed Al-Nahyan AFP / Karim SAHIB

World leaders have flocked to Abu Dhabi to pay their respects, demonstrating the rising prominence of the major oil exporter after the decline of some of the Middle East's traditional powers.

On Monday, Saudi Arabia's Crown Prince Mohammed bin Salman was in Abu Dhabi to offer his condolences.

A billboard displays the portrait of late UAE's president Sheikh Khalifa bin Zayed Al-Nahyan in the Emirate of Dubai on May 14, 2022, as the oil-rich Gulf state observes a period of mourning
A billboard displays the portrait of late UAE's president Sheikh Khalifa bin Zayed Al-Nahyan in the Emirate of Dubai on May 14, 2022, as the oil-rich Gulf state observes a period of mourning AFP / Giuseppe CACACE

The high-level US visit appears intended to repair a relationship that has deteriorated since Biden replaced Donald Trump in the White House in January 2021.

Ties have soured over issues including Abu Dhabi's refusal to condemn Russia's invasion of Ukraine and Washington's reopening of nuclear talks with Iran, long accused by Gulf states of creating regional chaos.

Britain's Prime Minister Boris Johnson offered his condolences on May 15, 2022 to Sheikh Mohamed bin Zayed al-Nahyan, new president of the UAE, over the death of his half-brother Sheikh Khalifa
Britain's Prime Minister Boris Johnson offered his condolences on May 15, 2022 to Sheikh Mohamed bin Zayed al-Nahyan, new president of the UAE, over the death of his half-brother Sheikh Khalifa Ministry of Presidential Affairs - Abu Dhabi via AFP / Abdullah AL-JUNAIBI

Yousef al-Otaiba, the Emirati ambassador to the US, admitted in March that relations were going through a "stress test".

Sheikh Hamdan bin Mohammed bin Rashid Al-Maktoum, Crown Prince of Dubai, inspects the open cockpit of an F-35 Lightning II multirole combat aircraft during the 2021 Dubai Airshow in the Gulf emirate on November 14, 2021
Sheikh Hamdan bin Mohammed bin Rashid Al-Maktoum, Crown Prince of Dubai, inspects the open cockpit of an F-35 Lightning II multirole combat aircraft during the 2021 Dubai Airshow in the Gulf emirate on November 14, 2021 AFP / Giuseppe CACACE

Blinken, who arrived in Abu Dhabi early Monday morning ahead of the delegation, offered his "warm congratulations" to Sheikh Mohamed on becoming president.

"He will carry on the legacy of Sheikh Khalifa bin Zayed. I look forward to continuing our two peoples' close cooperation," Blinken tweeted on Sunday.

John Kerry, the special presidential envoy for climate, and Brett McGurk, the National Security Council coordinator for the Middle East and North Africa, were also in the US team.

The UAE hosts US troops and has been a strategic partner to Washington for decades, but it has recently also grown closer to Russia economically and politically.

After a period of cosier ties under Trump, Biden shifted to a tougher stance on human rights and arms deals.

Relations were further strained when the UAE abstained from voting on a UN Security Council resolution demanding a Russian withdrawal from Ukraine.

Abu Dhabi has also shown no interest in increasing oil production after prices were sent sky-rocketing by the Russian invasion.

It has repeatedly urged Washington to "support re-designating" Yemen's Iran-backed Huthi rebels as a "foreign terrorist organisation" -- a label imposed by Trump but rescinded by the Biden administration.

The UAE is part of the Saudi-led military coalition that has been fighting for Yemen's internationally recognised government in a civil war against the Huthis since 2015.

In December, the UAE threatened to scrap its mega-purchase of US F-35 fighter jets, protesting stringent conditions set by Washington.

In January, three oil workers were killed in a Huthi drone and missile attack on Abu Dhabi. US forces based there fired Patriot interceptors to help thwart a further attack.