Fresh off an immense North Korean parade that revealed an arsenal of intercontinental ballistic missiles, rival South Korea and its allies are bracing for the possibility that Pyongyang's follow-up act will be bigger.

North Korea often marks significant dates by displaying military capability, and South Korean officials say there's a chance the country will conduct a nuclear test or a major missile launch around the founding anniversary of its military on Tuesday.

North Korea showed off its newest weapons, including prototype ICBMs and midrange solid-fuel missiles, at the April 15 parade honoring late state founder Kim Il Sung, grandfather of current ruler Kim Jong Un.

Kim Jong Un has the North aggressively pursuing a goal of putting a nuclear warhead on an ICBM capable of reaching the U.S. mainland.