VIENTIANE (Reuters) - U.S. President Barack Obama on Tuesday urged the full implementation of sanctions against North Korea, a day after it fired ballistic missiles into the sea, adding Washington had no interest in taking an offensive approach toward Pyongyang.

Speaking after a meeting in Laos with South Korean counterpart, Park Geun-hye, Obama said the firing of the missiles, when leaders of the Group of 20 major economies were at a summit in China, demonstrated the threat North Korea posed.

The United States, he said, would show "unwavering" support for its allies and North Korea's provocations would only lead to its further isolation.

Park said South Korea would respond "resolutely" to any provocation by the North and she echoed Obama's call for sanctions to be used, adding China had a role to play in implementing them.

(Reporting by Roberta Rampton; Writing by Martin Petty; Editing by Robert Birsel)