US Secretary of State John Kerry flew to Oman on Tuesday for Raytheon Co’s signing of an estimated $2.1 billion arms deal and to consult on Syria and Iran, U.S. officials told Reporters.

US Secretary of State John Kerry flew to Oman on Tuesday for Raytheon Co's signing of an estimated $2.1 billion arms deal and to consult on Syria and Iran, U.S. officials told Reporters.

Oman is expected to sign a letter of intent to purchase a ground-based air defense system that would help protect against cruise missile, drone or fighter aircraft attacks, a senior U.S. State Department official said.

Part of the sale has been previously disclosed. In October 2011, the U.S. Defense Department notified Congress of a proposed $1.25 billion sale of Avenger fire units, Stinger missiles, and Advanced Medium Range Air to Air Missiles to Oman.

However, it was unclear if Kerry would attend the signing expected on Tuesday or Wednesday.

Raytheon Chief Executive Bill Swanson told an earnings call last month that the company was making "considerable progress" on a number of foreign arms sales, including a deal to sell a ground-based air defense system to Oman.

Kerry's visit is the first stop on a week-long trip that will take him to Amman for talks on bringing Syria's warring parties to a peace conference and to Jerusalem and Ramallah to discuss reviving Zionist-Palestinian peace negotiations.

"It's basically a chance to do a signals check with an important ally," said a senior State Department official. "Oman is not a key player on Syria but, as an important player in the Gulf, I think it will be good to hear the sultan's views on the situation in the region writ large."

Kerry on Wednesday will meet in Jordan with senior officials from mostly Western and Arab states backing Syria's opposition to discuss how to bring both sides to the negotiating table.

The United States and Russia announced two weeks ago that they would try to bring the two sides together - possibly in Geneva in June - for a peace conference that would choose a transitional government.

Syria was hit by a violent unrest since mid-March 2011, where the Syrian government accuses foreign actors of orchestrating the conflict, by supporting the militant opposition groups with arms and money.