US Secretary of State Marco Rubio arrived in Abu Dhabi on Tuesday, the first stop on a tour of Gulf states aimed at showing solidarity with key allies hit hard by the Middle East war.The delicate mission comes with Gulf countries having paid a heavy economic price for the US and Israel's decision to go to war with Iran against their wishes, prompting Tehran to lash out at its regional neighbours.Iran's closure of the Strait of Hormuz cut off the majority of Gulf states' oil and gas exports, while its drone and missile attacks shattered their sense of safety and undermined the status of Qatar and the United Arab Emirates in particular as stable, peaceful havens for business and tourism. It marks the first visit by a senior US official to the region since the signing last week of an initial deal between Washington and Tehran aimed at ending the war for good.US Vice President JD Vance has taken the lead on those negotiations, which began at the weekend in Switzerland, with Rubio yet to comment.The diplomat arrived in Abu Dhabi on Tuesday evening, where he said no country was allowed to impose tolls or fees on the Strait of Hormuz."It's an international waterway. No country is allowed to charge tolls or fees on an international waterway. That's existing international law," he said as he arrived in the United Arab Emirates."I don't think we have anybody to convince around here in that regard. I think all the countries in this region would agree with us."Before the war, a fifth of global oil and liquefied natural gas travelled through the strait without charge.Iran is now pushing to charge some kind of fee for ships passing through.The US State Department earlier said Rubio would discuss the agreement with Iran, as well as efforts to ensure free transit of the Strait of Hormuz and peace and stability in the region.His next stop is Kuwait on Wednesday followed by Bahrain on Thursday, where he will attend a meeting of the six-member Gulf Cooperation Council.- 'Empowered Iran' -