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 even bigger.

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

Such moves could test the developing North Korea policies of President Donald Trump, who has reportedly settled on a strategy that emphasizes increasing pressure on Pyongyang with the help of China, North Korea’s only major ally, instead of military options or trying to overthrow the North’s government.

Recent U.S. commercial satellite images indicate increased activity around North Korea’s nuclear test site, and third-generation dictator Kim Jong Un has said that the country’s preparation for an ICBM launch is in its “final stage.”

Seoul’s Defense Ministry has said the North appears ready to conduct such “strategic provocations” at any time. South Korean Prime Minister Hwang Kyo-ahn, the country’s acting leader in place of ousted President Park Geun-hye, who has been arrested over corruption allegations, has instructed his military to strengthen its “immediate response posture” in case the North does something significant on the April 25 anniversary.

Trump and Japanese Prime Minister Shinzo Abe, in a phone call Monday, agreed to urge North Korea to refrain from what Abe called provocative actions. “The North Korean nuclear and missile problem is an extremely serious security threat to not only the international community but also our country,” the Japanese leader told reporters afterward.

There’s also a possibility that North Korea, facing potential changes in regional dynamics as Washington presses Beijing to pressure Pyongyang more aggressively, opts to mark the anniversary with a missile launch of lesser magnitude. North Korea separately fired what U.S. officials said were a Scud-type missile and a midrange missile earlier this month, but the launches were analyzed as failures.

While Trump has dispatched what he called an “armada” of ships to the region, including an aircraft carrier, U.S. officials have told The Associated Press that the administration doesn’t intend to militarily respond to a North Korean nuclear or missile test.

In a statement released late Friday, North Korea’s Foreign Ministry accused Trump of driving the region into an “extremely dangerous phase” with his sending of the aircraft carrier and said the North was ready to stand up against any kind of threated posed by the United States.

With typical rhetorical flourish, the ministry said North Korea “will react to a total war with an all-out war, a nuclear war with nuclear strikes of its own style and surely win a victory in the death-defying struggle against the U.S. imperialists.”

Under the watch of Kim, North Korea has been aggressively pursuing a decades-long goal of putting a nuclear warhead on an ICBM capable of reaching the U.S. mainland.

North Korea conducted two nuclear tests last year alone, which would have improved its knowledge on making nuclear weapons small enough to fit on long-range missiles. It also last year launched a long-range rocket that delivered a satellite into orbit, which Washington, Seoul and others saw as a banned test of missile technology.

On April 15, North Korea offered a fresh look at its advancing nuclear weapons and missiles program in a massive military parade in Pyongyang honoring late state founder Kim Il Sung, the grandfather of the current ruler.

The displayed military hardware included prototype ICBMs and new midrange solid-fuel missiles that can be fired from land mobile launchers and submarines, making them harder to detect before launch.

The parade also featured previously unseen large rocket canisters and transporter erector launcher trucks, or TELs. This indicated that North Korea was developing technologies to “cold-launch” ICBMs, ejecting them from the launch tubes before they ignite in midair, which would prevent its limited number of ICBM-capable launcher trucks from being damaged and also allow the missiles to be fired from silos.

Analysts say that the North is also likely developing solid-fuel ICBMs, and that some of the canisters might have contained prototypes.

North Korea had earlier shown signs it was working on a new ICBM.

In March, the North’s state media reported that the country successfully conducted a ground test of a new high-thrust rocket engine, which it said was a breakthrough for the country’s space program and efforts to create “Korean-style strategic weapons.” Kim was then quoted as saying “the whole world will soon witness what eventful significance the great victory won today carries.”

While North Korea almost certainly needs more time to create a solid-fuel ICBM, test launches for its existing liquid-fuel ICBMs, including the KN-08s and KN-14s, could come much sooner.

Experts say these missiles could one day be capable of hitting targets as far as the continental United States, although North Korea has yet to flight test them.

(AP)