North Korea said Friday it is ditching a nonaggression pact and all other peace agreements with South Korea, escalating tensions between the wartime rivals in a move seen as a possible prelude to an armed provocation. The communist nation also said it would no longer respect a disputed sea border with the South, raising the prospect for an armed clash around the Yellow Sea boundary - the scene of deadly skirmishes between the two navies in 1999 and 2002. South Korea said it regretted the North's latest move and warned it won't tolerate any attempt to violate the border. Analysts said Pyongyang appears to be trying to build up justification for an armed skirmish. "This signals that North Korea will stage a provocation" - probably near the maritime border, said Kim Yong-hyun, a North Korea expert at Seoul's Dongguk University. "The North is also trying to draw attention" from US President Barack Obama, he said.