RIYADH: The United States and Gulf Arab countries will sign an agreement on Sunday to coordinate their efforts against the financing of terrorist groups, a senior White House official said. The US President Donald Trump is visiting the region for the first-time since taking the office. Western officials believe that people living in wealthy Gulf countries have been an important source of funding for Sunni Islamist groups fighting in Iraq and Syria, including ISIS and al Qaeda. Saudi Crown Prince Mohammed bin Nayef and US Secretary of State Rex Tillerson will sign the memorandum of understanding in Riyadh, where the six-nation Gulf Cooperation Council (GCC) is holding a summit with Trump. “It’s the, we hope, farthest reaching commitment to not finance terrorist organizations that (the US) Treasury will be monitoring with each of their counterparts,” said Dina Powell, White House deputy national security adviser for strategy. “The unique piece of it is that every single one of them are signatories on how they’re responsible and will actually prosecute the financing of terrorism, including individuals.” The GCC comprises Saudi Arabia, Qatar, Kuwait, Oman, the United Arab Emirates and Bahrain.