The government said Pyongyang's request to postpone the ministerial talks is "incomprehensible."

The Unification Ministry on Sunday expressed regret over North Korea's request to postpone the 18th round of inter-Korean ministerial talks scheduled for late this month.

It said the North's objection to the exercise was difficult to understand as Seoul has explained that the purpose of the annual joint military exercises with U.S. forces is self-defense.

The ministry urged Pyongyang to abide by all bilateral agreements with Seoul to promote mutual trust and cooperation.