By Joey Roulette and Steve Gorman WASHINGTON (Reuters) -Two senior U.S. defense intelligence officials said on Tuesday the Pentagon is committed to determining the origins of what it calls “unidentified aerial phenomena” – commonly termed UFOs – but acknowledged many remain beyond the government’s ability to explain. The two officials, Ronald Moultrie and Scott Bray, appeared before a House of Representatives intelligence subcommittee for the first public U.S. congressional hearing on the subject in a half century. It came 11 months after a government report documented more than 140 cases of u…