A U.S. Treasury official on Thursday said donors located in the Gulf remain an important source of revenue for al Qaeda, but that the U.S. and regional allies were “making strides” in cutting off that financing.

“Donors located in the Gulf have traditionally been an important source of revenue for AQ. This remains the case, but we are making strides in cutting off their financial networks,” Daniel Glaser, assistant secretary for terrorist financing at the U.S. Department of Treasury, said at a hearing.

He said the Gulf countries have taken a wide range of actions, and called Saudi Arabia a “regional leader” in combating terrorist financing, amid suspicions in Congress the kingdom is not doing enough to choke off support for terrorists.

“All Gulf countries have now passed counter-terrorism laws that criminalize terrorist financing, and have enhanced financial controls across the charitable sector to ensure that funds intended for humanitarian objectives do not benefit terrorist activity,” he said.