Reuters- U.S. Secretary of State Rex Tillerson and Defense Secretary Jim Mattis said on Monday that they did not expect a decision by some�Persian Gulf countries to sever ties with Qatar to affect the fight against terrorism but urged them to address their differences.

Saudi Arabia, Egypt, the United Arab Emirates and Bahrain severed their ties with Qatar on Monday, accusing it of supporting terrorism, in an unprecedented breach between the most powerful members of the�Persian Gulf Cooperation Council.
The coordinated move dramatically escalates a dispute over Qatar's support for the Muslim Brotherhood, the world's oldest Islamist movement, and adds accusations that Doha even backs the agenda of regional arch-rival Iran.
"I do not expect that this will have any significant impact, if any impact at all, on the unified - the unified - fight against terrorism in the region or globally," Tillerson told reporters in Sydney after meetings between Australian and U.S. foreign and defense ministers.

The region plays an important role for the U.S. military in the fight against Islamic State. Bahrain houses the U.S. Navy's Fifth fleet, which patrols the seas of the Middle East and Central Asia, while Qatar is home to the Al Udeid Airbase, from where the United States carries out airstrikes against militants in the region.

The decision comes during a critical moment in the fight against Islamic State. The Syrian Kurdish YPG militia said on Saturday that it was days away from a U.S.-backed operation by Syrian forces to capture Islamic State's Syrian "capital" of Raqqa.

The Syrian Democratic Forces (SDF), an alliance of Kurdish and Arab militias backed by the U.S.-led coalition, has been encircling Raqqa since November in a multi-phased campaign to drive Islamic State from the city where it has planned attacks on the West.

The assault on Raqqa will pile more pressure on Islamic State's self-declared "caliphate" with the group facing defeat in the Iraqi city of Mosul and being forced into retreat across much of Syria, where Deir al-Zor is its last major foothold.

Tillerson urged the Persian Gulf Cooperation Council nations to sort out their differences and said that the United States was willing to play a role in helping the countries address their differences.

(Reporting by Jane Wardell; Editing by Nick Macfie)