North Korea ran a tactical nuclear attack simulation over the weekend by test firing two long-range cruise missiles with mock atomic warheads, state media confirmed Sunday.

The Korean Central News Agency (KCNA) said the operation early Saturday was a "counteraction drill" in response to joint military activity by U.S. and South Korean forces that the agency said had escalated tensions in the region.

"A firing drill for simulated tactical nuclear attack was conducted at dawn of Sept. 2 to warn the enemies of the actual nuclear war danger," KCNA reported.

"Two long-range strategic cruise missiles tipped with mock nuclear warheads were fired" from North Korea's west coast into the sea to the south, it said.

South Korea's Joint Chiefs of Staff (JCS) said Saturday that an unspecified number of cruise missiles were launched at around 4 a.m. (7 p.m. GMT) toward the Yellow Sea, adding that the specifications of the missiles were being evaluated.

A JCS official dismissed Pyongyang's claims, calling them "exaggerated," the South Korean Yonhap news agency reported Sunday.

KCNA said the United States and South Korea were pursuing "confrontation hysteria" with their latest joint military drills.

Analysts said the North's claims were aimed at deterrence.

North Korea's claims "suggest the Kim regime is desperate to deter an increasingly capable South Korea, including Seoul's strengthened alliance with Washington", said Leif-Eric Easley, a professor at Seoul's Ewha University.

"Pyongyang's rhetoric actually goes far beyond the logic of deterrence, probably to shore up domestic political legitimacy, which is an ominous sign for inter-Korean relations," he told AFP.

Cho Han-bum, a senior research fellow at the Korea Institute for National Unification, said the weekend launches were aimed at proving North Korean capabilities to the South and its allies.

"North Korea is moving according to their own plan, which is to strike major military facilities on the Korean peninsula and strike U.S. bases in Japan at the same time," he said, adding the two long-range cruise missiles fired at the weekend targeted Japan.

"The key point is that North Korea is countering South Korea and the United States with nuclear operation units rather than conventional weapons," Cho told AFP.

Arms production

In a separate report, KCNA said North Korean leader Kim Jong Un had inspected "a major munitions factory", the latest in a string of visits to weapons plants in recent weeks.

Kim "expressed satisfaction" and stressed the importance of the factory "in bolstering up the armed forces of the DPRK", KCNA reported, using the acronym for North Korea's official name.

North Korea has conducted a record number of weapons tests this year, and last month failed in its second attempt to put a spy satellite into orbit.

Seoul and Washington have ramped up defense cooperation in response, staging joint military exercises with advanced stealth jets and U.S. strategic assets.

Last week, Kim visited a training command post where he detailed future war plans, including "making simultaneous super-intense strikes" at core military posts in the South.

Relations between the two Koreas are at their lowest point in years, and diplomacy has stalled after failed attempts to discuss Pyongyang's denuclearization.

Kim has declared North Korea an "irreversible" nuclear power and called for ramped-up arms production, including of tactical nuclear weapons.