On the eve of his 10-day trip to the Asia Pacific, U.S. Secretary of Defense Chuck Hagel warned North Korea to stop its provocations. On Monday, North Korea and South Korea exchanged artillery shell rounds as a North Korean military exercise crossed into South Korean waters. North Korea fired more than 100 rounds, which were met by 300 rounds from South Korea. Hagel was briefed Monday on the situation by U.S. General Curtis Scaparrotti, Commander of the UN Command, Republic of Korea-U.S. Combined Forces Command. "... the North Koreans," Hagel said at a press conference Monday, "have to stop these provocative actions. And we have been very clear on that. And obviously when I'm in China, that will be a subject that I will discuss with my counterpart in China."