U.S. Defense Secretary Jim Mattis on Thursday credited U.S.-championed international pressure on North Korea over its nuclear weapons and missile programs for Pyongyang’s offer of talks with South Korea, but added it was too soon to say whether the North Korean gesture was meaningful.

“I wouldn’t read too much into it because we don’t know if it’s a genuine olive branch,” Mattis said during an impromptu, off-camera press briefing at the Pentagon, according to Reuters.