Apache helicopters are ready to take off at U.S. Camp Humphreys in Pyeongtaek, Gyeonggi Province, Aug. 19. Yonhap

North Korea on Friday denounced the United States' approval of a potential sale of Apache attack helicopters to South Korea as a provocative act that deliberately aims to increase security instability in the region.

A North Korean foreign ministry official issued the statement after the U.S. announced a decision earlier this week to approve a proposed sale to South Korea of 36 AH-64E Apache attack helicopters and other items for $3.5 billion.

"This is a reckless provocative act of deliberately increasing the security instability in the region," the statement said, noting that the approval came at a time when tensions on the Korean Peninsula were high due to joint military exercises under way between the South and the U.S.

"The U.S. is now getting more active in its arms sale to Japan, ROK and other allies in the Asia-Pacific region, and this is a challenge to security in the region that cannot be overlooked," it said, according to the Korean Central News Agency.

The North warned it will steadily conduct necessary military activities to control the military imbalance and instability in the region as the U.S. is determined to provide "war hardware and lethal equipment" to its allies.

"Since the U.S. is keen on the provision of war hardware and lethal equipment to its allies in the region, the DPRK's strategic deterrence will be further strengthened to protect the national security and interests and the regional peace," it said.

Seoul and Washington launched their annual Ulchi Freedom Shield exercise Monday for an 11-day run in a bid to bolster their joint defense readiness against North Korea's evolving military threats. North Korea has long denounced the allies' joint military drills as a rehearsal for an invasion. (Yonhap)