North Korea could resort to nuclear weapons in a crisis "more easily" as it is making "significant" progress toward implementing a more robust nuclear strategy, a US think tank report said Thursday.

The conservative Heritage Foundation released the 2024 Index of US Military Strength, providing its analysis of threats from North Korea, China, Iran and Russia, as well as terrorist threats from the Middle East and North Africa.

Calling the North a "perennial" problem in Asia, the report delved into the North's military capabilities that it said are not "on the same existential scale" as the threat posed by China or Russia, but threaten to undermine not only regional security but also the US homeland.

"The increasing rate and diversity of North Korea's missile launches shows that Pyongyang is making significant progress toward implementing a more capable and flexible nuclear strategy, including preemptive strikes with strategic, tactical and battlefield nuclear weapons," the report said.

"During a crisis, the threshold for the use of nuclear weapons could therefore be breached more easily," it added.

In defiance of international criticism, Pyongyang has been doubling down on its nuclear and missile programs as seen in its recent launches of various missiles, including a solid-fuel intermediate-range ballistic missile tipped with a hypersonic warhead and strategic cruise missiles.

The report warned that greater North Korean nuclear capabilities could undermine the effectiveness of existing allied military plans and exacerbate growing concerns by US allies about Washington's willingness to risk a nuclear attack to defend its allies.

"A more survivable nuclear force could lead North Korea to conclude that it has immunity from any international response and therefore act even more belligerently and use nuclear threats to coerce Seoul into accepting regime demands," the report said.

"The regime could use threats of nuclear attack to force Tokyo to deny US forces access to Japanese bases, ports and airfields during a Korean conflict. Pyongyang might also assume that conditions for military action had become favorable if it believed that the US extended deterrence guarantee had been undermined," it added.

The report also took note of weaknesses of the North Korean military, like its old weapons systems for ground forces.

"Its naval and air forces would not be expected to last long in a conflict with South Korea and the US, but they would have to be accounted for in any defense by South Korea," it said.

"Pyongyang's ground forces are largely equipped with older weapons, but they also are extensive and forward-deployed. Thousands of artillery systems deployed near the demilitarized zone could inflict devastating damage on South Korea, especially Seoul, before allied forces could attrite them." (Yonhap)