By Alex Jensen
SEOUL
Pyongyang called for the withdrawal of United States troops from the Korean Peninsula this month, according to a letter unveiled by the United Nations on Monday.
North Korea's U.N. Ambassador Ja Song-nam blamed Washington for regional tensions in the message sent last Tuesday.
The North's nuclear weapon ambitions have been regularly frowned upon by both the U.S. and the wider international community.
But Ja's letter turned the tables, accusing the U.S. of seeking "a pretext for arms buildup."
Nearly 30,000 American military personnel are based in South Korea as a legacy of the 1950-53 Korean War, which ended only in a truce rather than a peace treaty.
Late August saw the start of a thaw in inter-Korean tensions, as Seoul and Pyongyang reached a breakthrough cooperation pact.
But North Korea's complaint to the U.N. stated that joint South-U.S. military drills have developed into a "main factor of aggravating confrontation and distrust."
Pyongyang also warned via its letter that it could launch a covert attack -- of the kind that it has repeatedly denied responsibility for.
The North has in recent years refused to admit to the 2010 sinking a South Korean warship, a series of cyber attacks and early August's border landmine blasts.
North Korea's latest threat made clear that "another incident of unknown origin" could occur if the U.S. does not withdraw its troops from the peninsula.
