Story highlights Corker sent the letter to Secretary of State Rex Tillerson

Corker has a unique perch in Congress to try to force the countries to a resolution

(CNN) Senate Foreign Relations Chairman Bob Corker sent a letter to Secretary of State Rex Tillerson on Monday saying he will block foreign military sales to members of the Gulf Cooperation Council until they can resolve their dispute with Qatar.

Saudi Arabia, the United Arab Emirates, Bahrain and Egypt cut ties with Qatar on June 5, accusing the country of supporting terrorism and destabilizing the region.

As chairman of the Foreign Relations Committee, Corker has a unique perch in Congress to try to force the countries to a resolution because the top Republican and Democrat on the respective House and Senate committees informally sign off on arms deals before they are formally notified to Congress. The full body then votes approve or disapprove of the sale.

Under the foreign arms sale process with the Pentagon and State Department, if any one of those four lawmakers disapproves of a sale, it does not move forward to be formally notified to Congress.

"I could not have been more pleased with (President Donald Trump's) recent trip to Saudi Arabia. The unity of the Gulf States and their commitment to security cooperation were welcome steps forward," Corker wrote in the letter to Tillerson.

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