By Arshad Mohammed and Adrian Croft
ANTALYA, Turkey (Reuters) - A clearer security arrangement between Gulf countries and the United States is critical to fighting terrorism, U.S. Secretary of State John Kerry said on Wednesday, ahead of a summit in Washington with Arab leaders.
U.S. President Barack Obama will meet with Saudi Arabia's Crown Prince Mohammed bin Nayef and Deputy Crown Prince Mohammed bin Salman in Washington's Oval Office later, before the summit with the six-nation Gulf Cooperation Council (GCC).
"Defining ... a clearer defence arrangement between the GCC and other friendly countries and the United States is going to be critical to helping to push back against the terrorism, as well as some of the other activities that take place in that region that are unsettling to all of those countries," Kerry said.
He was speaking to reporters on the sidelines of a meeting of NATO foreign ministers in Antalya, Turkey, before flying back to Washington to attend a dinner at the White House with Obama and GCC officials.
Obama invited the GCC nations - Saudi Arabia, Kuwait, Bahrain, Qatar, the United Arab Emirates and Oman - after six world powers reached a framework agreement with Iran that would give Tehran sanctions relief for reining in its nuclear programme.
The Gulf nations are worried a nuclear deal would strengthen Iran at a time when the majority Shi'ite nation is exerting influence in regional trouble spots including Yemen and Syria.
Kerry said he was very hopeful of a successful conclusion to the Iran nuclear negotiations.