A new round of six-nation talks on North Korea's nuclear ambitions began Tuesday with the United States saying it does not intend to invade the North, and Pyonyang promising to work toward a nuclear-free Korean Peninsula _ opening moves that indicate both sides want progress toward a settlement, AP reported. After a 13-month boycott by North Korea, which cited «hostile» U.S. policies, delegates struck an amiable tone before the meeting, smiling and clasping hands for a group photo. South Korea, China, Japan and Russia were the other participants. Both the chief U.S. and North Korean envoys pledged to make progress following three earlier rounds of talks that produced no breakthroughs. «These talks are at a critical juncture,» U.S. Assistant Secretary of State Christopher Hill said at the opening ceremony. «We do not have the option of walking away from this problem.» His North Korean counterpart, Vice Foreign Minister Kim Kye Gwan, said «the fundamental thing is to make real progress in realizing the denuclearization of the Korean Peninsula.» «This requires very firm political will and a strategic decision of the parties concerned that have interests in ending the threat of nuclear war,» Kim said. «We are fully ready and prepared for that.»