North Korean leader Kim Jong Un appeared in a massive parade in the capital city on Saturday celebrating the birthday of his late grandfather and North Korea founder Kim Il Sung.

North Korean state television showed Mr. Kim, wearing a black suit and white shirt, stepping out of a black limousine and saluting his honor guard before walking down a red carpet. He then walked up to a podium and clapped with senior government officials to address the thousands of soldiers and a massive crowd taking part in the parade at Kim Il Sung Square.

The parade may also feature some of the country’s most valuable military hardware, such as its prototype intercontinental ballistic missiles.

The festivities take place amid concerns that North Korea is possibly preparing its sixth nuclear test in a decade or a rocket launch of significance, such as its first flight test of an ICBM.

Mr. Kim, a 30-something leader who took power in late 2011, emphasizes nuclear weapons as the foundation of his national defense strategy. The country under his watch has been aggressively pursuing a goal of putting a nuclear warhead on an ICBM capable of reaching the continental United States.

In his annual New Year’s address, Mr. Kim said that North Korea’s preparations for an ICBM launch have “reached the final stage.” U.S. satellite imagery suggests the country could conduct another underground nuclear test at any time.

North Korea conducted two of such tests last year alone, which analysts say would have taken the country a step forward in gaining the knowledge to make nuclear weapons small enough to fit on long-range missiles. The North also last year launched a long-range rocket that put a satellite into orbit, which Washington, Seoul and others saw as a banned test of missile technology.

Amid the elevated tensions, the United States a few days ago dispatched what President Donald Trump called an “armada” of ships in a show of force, including an aircraft carrier, into waters off the Korean Peninsula.

The move, coupled with the U.S. retaliatory strikes against Syria over a chemical weapons attack on civilians, touched off fear in South Korea that the United States was preparing for military action on the North.

A U.S. military official, who requested anonymity to discuss planning, said the United States doesn’t intend to use military force against North Korea in response to either a nuclear test or a missile launch.

Pyongyang has expressed anger over the annual spring military exercises the U.S. holds with South Korea, which it considers an invasion rehearsal. It has warned of a nuclear attack on the United States in retaliation for any sign of aggression. That threat, however, has been made numerous times in the past.