The United States and the Republic of Korea will work to make sanctions against North Korea more effective by closing loopholes after the country launched three missiles into the Sea of Japan Sunday while world leaders met in China for the G-20 summit, President Barack Obama said Tuesday. “These launches are provocative,” he said after a meeting with South Korean President Park Geun-Hye in Laos, where he travelled after China. “North Korea needs to know that provocations will only invite more pressure and further deepen its isolation.” US Strategic Command tracked what it assessed to be three missile launches near the city of Hwangju, North Korea, at 10:13 p.m. Central Daylight Time, on Sept. 4, according to a STRATCOM release. Two of the three missiles were believed to be intermediate range ballistic missiles, and STRATCOM is still assessing the third. NORAD determined the missiles did not pose a threat to North America. The launches were the latest in a string of recent North Korean missile tests. President Park said the continued “launches are fundamentally threatening the security of both the Korean Peninsula and Northeast Asia.” She said the US and South Korea have agreed to continue talking with China about implementing the sanctions. “I send a stern warning that the continuation of such reckless provocations will lead North Korea down the path of self-destruction,” she said of Sunday’s launches.