WASHINGTON - Projecting a united front, President Obama and South Korea's new leader warned North Korea on Tuesday against further nuclear provocations, with Obama declaring that the days when Pyongyang could "create a crisis and elicit concessions" were over.
Obama also disputed the notion that his cautious response to reported chemical weapons use in Syria - a move he had said would cross a "red line" - could embolden North Korea's unpredictable young leader and other U.S. foes.
"Whether it's bin Laden or Gadhafi, if we say we're taking a position, I would think at this point the international community has a pretty good sense that we typically follow through on our commitments," Obama said, referring to the al-Qaida commander Osama bin Laden and former Libyan leader Moammar Gadhafi, both of whom were killed during Obama's watch.
Tuesday's meetings between Obama and South Korean President Park Geun-hye followed months of increased tensions on the Korean Peninsula. North Korea conducted an underground atomic test in February and had appeared ready for another.
New U.S. intelligence assessments also showed for the first time that North Korea may have the know-how to launch a nuclear-armed missile, though American officials say Pyongyang still appears to lack the capability to carry out an attack.
Ahead of Tuesday's talks, the North appeared to send mixed messages. U.S. officials said Pyongyang removed from a launch pad a set of medium-range ballistic missiles that had been readied for possible test-firing. But North Korea also warned the U.S. and South Korea that it would retaliate if joint military exercise between the two allies resulted in any shells landing on its territory.
Speaking at a joint news conference at the White House, Obama and Park warned Pyongyang of unspecified consequences if it pressed ahead with provocative actions, with Obama vowing to protect the U.S. and its allies using both "conventional and nuclear forces."
"Should North Korea choose the path to becoming a responsible member of the community of nations, we are willing to provide assistance, together with the international community," Park said.
Analysts see some of North Korea's recent bluster as an attempt by the country's new leader, Kim Jong Un, to establish himself as a power player, both within his own country and in the international community.
Obama said he knew little about Kim personally and has never spoken to him, but added that his actions were leading him down a dead end.
"There's going to have to be changes in behavior," Obama said. "We have an expression in English, 'Don't worry about what I say, just watch what I do.' "
North Korea ratcheted up its provocations this year after the U.N. Security Council tightened sanctions in response to the February nuclear test, its third since 2006.