Negotiators from the United States and North Korea will sit down with other regional powers for the first time in 13 months to determine the nuclear fate of the peninsula, with Pyongyang's first-ever atomic weapons test adding pressure for results that won't come easy. The six countries meeting this Monday in Beijing for the talks - also including China, Japan, Russia and South Korea - will pick up where they left off in November 2005, seeking to finally take steps to implement the only agreement ever reached at the negotiations a month before they ground to a halt. The main US envoy, Assistant Secretary of State Christopher Hill, said this week in Washington that the "purpose is to come to an agreement and have some effect on the ground." But he remained cautious. "I don't want to be optimistic that we are going to achieve that, but that is certainly the objective," Hill said.