WASHINGTON, June 16 (Reuters) - The director of the U.S. Central Intelligence Agency, John Brennan, said on Thursday that the United States and its allies have made gains against Islamic State, but he expects the group to change its tactics to make up for lost territory.

"To compensate for territorial losses, ISIL (Islamic State) will probably rely more on guerrilla tactics, including high-profile attacks outside territory it holds," Brennan testified to the Senate Intelligence Committee.

(Reporting by Patricia Zengerle; Editing by Paul Simao) ((patricia.zengerle@thomsonreuters.com, ; 001-202-898-8390; Reuters Messaging: patricia.zengerle.reuters.com@reuters.net))