WASHINGTON—U.S. lawmakers briefed Thursday on the recently revealed NSA surveillance programs trained their fire on the self-described source of the leaks, Edward Snowden, suggesting he may be cooperating with the Chinese government.

Without presenting any evidence, the top two lawmakers on the House Intelligence Committee raised questions about whether Mr. Snowden, 29, has defected to Hong Kong and has any ties to China. "Clearly, we're going to make sure that there's a thorough scrub of what his China connections...