Seoul (AFP) - North Korea's recent missile tests were "tactical nuclear" drills personally overseen by leader Kim Jong Un, state media said Monday, adding the launches were a response to US-led joint military exercises in the region.

Kim has long wanted to develop tactical nukes -- smaller, lighter weapons designed for battlefield use -- and made it a top priority at a key party congress in January 2021.

The country revised its nuclear laws last month, envisaging a wide array of scenarios in which it could use its nukes, with Kim declaring North Korea an "irreversible" nuclear power -- effectively ending the possibility of denuclearisation talks.

Since then, Seoul, Tokyo and Washington have ramped up combined naval exercises, including deploying the nuclear-powered aircraft carrier the USS Ronald Reagan to the area twice, infuriating Pyongyang, which sees the joint drills as rehearsals for invasion.

In response, North Korea "decided to organise military drills under the simulation of an actual war", the official KCNA reported.

North Korean army units involved in "the operation of tactical nukes staged military drills from September 25 to October 9 in order to check and assess the war deterrent and nuclear counterattack capability of the country," the report said.

"Kim Jong Un, general secretary of the Workers' Party of Korea and chairman of its Central Military Commission, guided the military drills on the spot," it added.

KCNA said that "tactical nuclear operations units" had conducted seven launching drills that had allowed North Korea's nuclear forces to display their "militant effectiveness and actual war capabilities", KCNA added.

Systems deployed?

North Korea also released multiple photographs of the recent missile launches, tests and exercises, showing Kim Jong Un overseeing them all, giving orders and posing with smiling soldiers.

"They're pursuing a tactical nuclear weapon for sure," said US-based security analyst Ankit Panda.

"I suspect they'll gradually nuclearize many of their new short-range missiles, including the maneuvering missiles."

The fact that North Korea has described all seven of its recent missile launches as being linked to "tactical nuclear operations units" is significant, he added.

"This is interesting because this includes (everything) from short-range ballistic missiles to IRBMs (and a new short-range SLBM)," he wrote on Twitter.

The fact that North Korea was not framing the recent launches as tests of the missiles themselves, but of the units that launch them, was also significant, analysts said.

"That suggests these systems are deployed," Jeffrey Lewis of the Middlebury Institute of International Studies wrote on Twitter. 

'Military threat'

With talks long stalled, Pyongyang has doubled down on its banned weapons programmes, firing an intermediate-range ballistic missile (IRBM) over Japan last week, with officials and analysts warning it had completed preparations for another nuclear test.

The United States redeployed the nuclear-powered aircraft carrier to waters east of South Korea as part of a broad-ranging military response to Pyongyang's IRBM test, which also included joint bombing and missile drills.

North Korea has repeatedly slammed the carrier's redeployment, saying Monday that the US was "openly posing a military threat to the DPRK", KCNA said, using the North's official name.

North Korea also said it had carried out "a large-scale combined air-attack drill", also overseen by Kim, in which it said "more than 150 fighter planes of different missions took off simultaneously for the first time in history".

Seoul's military said it had scrambled 30 fighter jets Thursday after 12 North Korean warplanes staged a rare "formation flight north of the inter-Korean air boundary [and] conducted air-to-surface firing drills".

"Kim probably wants to tell the US and South Korea that any demonstrations of alliance solidarity and readiness will be in vain," Rand corporation analyst Soo Kim told AFP. 

"We probably won't see North Korea backing down anytime soon, and from all appearances, it appears the allies may not fold easily this time, either."