MUSCAT US Secretary of State John Kerry arrived in Oman on Tuesday aiming to help finalise an estimated $2.1 billion deal to supply a US-made air-defence system to the Gulf nation.One of the main focuses of Kerry’s trip was to applaud the signing of a letter of intent between Muscat and US manufacturer Raytheon ahead of talks to negotiate the final contract, officials told reporters on the flight to Oman.“In January the Omanis made a decision to buy a ground-based air defence system produced by Raytheon... something that the secretary advocated for when he was in the Senate,” a senior State Department official said.Kerry had strongly backed the bid by the company based in his home state of Massachusetts, before taking office as the new top US diplomat on February 1.“Part of the goal of this is to push US commercial interests, to demonstrate to Oman that these are important to this administration,” the official added.After arriving, Kerry first headed for talks with Oman’s ruler, Sultan Qaboos, at his vast beige and white palace complex, an oasis of green and palm trees set against a backdrop of mountains in the desert landscape. The final details of the Raytheon deal have yet to be worked out, but officials said the contract expected to be signed on Wednesday would be worth an estimated $2.1 billion (1.6 billion euros).“It will further integrate the defensive systems in the Gulf, which is something we have been working on quite a bit within the GCC,” the official said, referring to the Gulf Cooperation Council. “There are similar systems elsewhere in the Gulf,” she said. “Oman has also recently brought a second tranche of F-16s so this is a way of continuing our relationship in the defence arena and will have pluses in terms of interoperability.”US officials said the deal to supply 12 F-16s was sealed in 2011 for delivery through 2014. Kerry will also discuss the war in Syria with Oman, a key Gulf ally, which also maintains close ties to Iran.The US and the West has condemned Iran for helping to prop up Syrian President Bashar al-Assad in his bloody fight to stay in power against a determined rebellion now in its third year.The United States and Russia are working to bring together the Assad regime and the opposition at a conference to map out a path for a political transition and end the war that has claimed moe than 94,000 lives.Russia has insisted Iran should be invited to the peace conference, whose date and venue has not yet been agreed. But the West is wary of engaging Tehran in such global efforts.“Oman is not a key player in Syria, but as an important player in the Gulf it will be good to hear the sultan’s views on the situation in the region writ large,” the State Department official said.“So it’s a chance basically to do a signals check with an important ally.” Kerry is also likely to urge Omani leaders to try to intercede with Iran for the release of two jailed American-Iranians.Former US Marine Amir Mirzai Hekmati, 29, was detained in August 2011 while visiting his elderly grandmother on his first trip to Iran. He was accused of being a CIA operative.Kerry has also said he is “deeply concerned” about the fate of an Iranian-American Christian pastor Saeed Abedini, who has been sentenced to eight years in jail.The United States is also still seeking information about retired FBI agent Robert Levinson, who went missing six years ago while on a trip to Iran.On Wednesday Kerry will head to Amman for a meeting of the Friends of Syria.While the beginning of his eight-day trip is likely to focus on Syria, Kerry then travels for talks Thursday and Friday in Israel and with the Palestinian leadership.He is seeking to kickstart the peace process, which has languished for more than two years, with a series of parallel moves aimed at restoring trust.