The Democratic People's Republic of Korea (DPRK) on Friday accused the United States and Japan of reckless behavior, saying the two are strengthening their military alliance.

"Frightened by a series of the great successful ICBM (intercontinental ballistic missile) test-launches by the DPRK, the U.S. and the Japanese reactionaries are going more reckless than ever before in their moves to 'tighten the alliance' against the DPRK," said the official daily Minju Joson (Democratic Korea).

The official media also said the United States and Japan are resorting to a strategy of sanctions to isolate and stifle the DPRK while staging joint military games aimed at making a "preemptive strike" against the DPRK.

"This is an intolerable challenge to the DPRK as it is a revelation of the unchanged ambition of aggression of the U.S. and the Japanese reactionaries who have imposed untold sufferings and misfortune on the Korean nation for several decades," it said.