SEOUL (AFP) -- North Korea on Tuesday condemned U.S.-South Korean joint military exercises, amid reports that its own jet fighters staged a major drill this month.

The North's military will reinforce its combat posture and mercilessly punish ""aggressors,"" the official Korean Central News Agency said in a commentary.
""Our revolutionary armed forces will never sit idle in the face of reckless war-provoking schemes by the U.S. imperialists and the Lee Myung-Bak group,"" it said.
The commentary was published by major North Korean newspapers, said the agency, which frequently attacks South Korea's conservative President Lee.
It accused Washington and Seoul of destroying peace and security on the Korean peninsula by driving inter-Korean relations to ""an irreversible catastrophe"".
The North routinely describes exercises involving U.S. and South Korean troops as a prelude to invasion, while the United States and South Korea say they are purely defensive.
The hardline communist country has stepped up military drills since Lee took power in February. The South Korean leader has promised to take a firmer line in cross-border relations.
A six-nation nuclear disarmament deal is also faltering, with the North making preparations to restart its plutonium-producing reactor.
And there is uncertainty about the health of leader Kim Jong-Il, after South Korean officials reported he is recovering from a stroke.
The South's Yonhap news agency said North Korean jet fighters including MiG-21s staged major exercises this month off the west coast near the border with China.
The Defense Ministry refused comment on the report. But a military official told AFP on condition of anonymity: ""This year North Korean troops have staged more drills than before.""
The two Koreas have remained technically at war since their 1950-1953 war ended only with an armistice and not a peace pact. Some 28,500 U.S. troops are based in the South to deter any attack.