North Korea displayed new submarine-launched ballistic missiles under development and other military hardware in a parade that underlined leader Kim Jong Un’s defiant calls to expand the country’s nuclear weapons program.

State media said Kim took center stage in a parade celebrating a major ruling party meeting in which he vowed maximum efforts to bolster the nuclear and missile programme that threatens Asian rivals and the American homeland to counter what he described as US hostility.

Kim’s comments are likely intended to pressure the incoming US government of Joe Biden, who has previously called the North Korean leader a “thug” and accused Trump of chasing spectacle rather than meaningful curbs on the North’s nuclear capabilities. Kim has not ruled out talks, but said the fate of bilateral relations depends on whether Washington abandons its hostile policy toward North Korea.

North Korean state TV aired edited footage of the parade which showed thousands of civilians roaring and fireworks exploding overhead as troops rolled out some of the country’s most advanced weapons, including submarine-launched ballistic missiles described by the official Korean Central News Agency as the “world’s most powerful weapon.” The new type of submarine-launched missiles was larger than the ones North Korea previously tested.

The North also displayed a variety of solid-fuel weapons designed to be fired from mobile land launchers, which potentially expand its capability to strike targets in South Korea and Japan, including US military bases there. KCNA said the parade featured other missiles capable of “thoroughly annihilating enemies in a pre-emptive way outside (our) territory.” But it wasn’t immediately clear whether the description referred to intercontinental ballistic missiles.

North Korea has been developing submarine-launched ballistic missile systems for years. Acquiring an operational system would alarm its rivals and neighbors because missiles fired from under water are harder to detect in advance.