North Korea warned Thursday it will react to upcoming joint U.S-South Korean joint military exercises with a "strong measure of self-defense," condemning the drill as a preparation for a nuclear attack on the North.

The weeklong exercises are scheduled to begin Saturday with 20,000 American troops, along with the aircraft carrier USS Abraham Lincoln, and an undisclosed number of South Korean soldiers.

"The U.S. decision to let carrier Abraham Lincoln and its task flotilla participate in the exercises goes to clearly indicate what reckless and dangerous phase the U.S. moves for a pre-emptive attack have reached," a spokesman for the North's Foreign Ministry said in statement carried by the North's official Korean Central News Agency.

The United States and South Korea have characterized the exercise as purely defensive, but the North Korean spokesman said the country "will react to it with a strong measure for self-defense." He did not specify what that would entail.

The spokesman also warned that U.S. sanctions against the North will not make Pyongyang change its stance. He did not elaborate but the comment appeared to refer to the stalled talks on his country's nuclear weapons program.

The communist country has refused to resume the six-nation nuclear disarmament talks since November, demanding that Washington lift financial restrictions imposed on a Macau bank and North Korean companies for alleged complicity in counterfeiting and money laundering.

Washington says the financial actions are separate from the nuclear talks.

The North has said that the resumption of the six-party talks and resolution of the nuclear issue depends entirely on the U.S. attitude.

The talks — which involve the two Koreas, the U.S., Japan, China and Russia — produced a breakthrough accord in September when the North agreed to abandon its nuclear programs in exchange for aid and security assurances. Follow-up negotiations have stalled over the North's anger at U.S. sanctions.

Earlier this week, North Korea suggested it had the ability to launch a pre-emptive attack on the United States and said it had built atomic weapons to counter the U.S. nuclear threat.