SEOUL, South Korea >> A North Korean missile exploded during launch Sunday, U.S. and South Korean officials said, a high-profile failure that comes as a powerful U.S. aircraft supercarrier approaches the Korean Peninsula in a show of force.

It wasn’t immediately clear what kind of missile was test-fired from the east coast city of Sinpo. But the failure will sting in Pyongyang because it comes a day after one of the biggest North Korean propaganda events of the year— celebrations of the 105th birthday of late North Korea founder Kim Il Sung, the current leader’s grandfather.

The North’s test firing can be seen as a message of defiance to the Trump administration in Washington, coming as it does on the day U.S. Vice President Mike Pence is set to arrive in Seoul for talks on North Korea.

President Donald Trump was uncharacteristically quiet about the failed launch. In a statement, Defense Secretary Jim Mattis said Trump and his military team “are aware of North Korea’s most recent unsuccessful missile launch. The president has no further comment.”

Washington and Seoul will try hard to figure out what exactly North Korea fired. This matters because while North Korea regularly launches short-range missiles, it is also developing mid-range and long-range missiles meant to target U.S. troops in Asia and, eventually, the U.S. mainland.

The ultimate goal is to have a full array of nuclear-tipped missiles in response to what Pyongyang says is hostility by Washington and Seoul meant to topple its government. North Korea is thought to have a small arsenal of atomic bombs and an impressive array of short- and medium-range missiles.

Many outside analysts believe that North Korea has not yet mastered the technology to build warheads small enough to place on long-range missiles, though some civilian experts say North Korea can already build nuclear-tipped shorter range missiles that have South Korea and Japan within its striking range.

The U.S. Pacific Command said in a statement that Sunday’s missile exploded on launch. South Korea’s Defense Ministry said it was analyzing exactly how the North Korean launch failed. Neither military knew what kind of missile was fired.

In Seoul, South Korea’s presidential office convened a national security council meeting to examine security postures.

Always high animosity has risen on the Korean Peninsula in recent months, as the United States and South Korea conduct annual war games that North Korea claims are invasion preparation and the North prepared for Saturday’s anniversary celebrations. A U.S. aircraft carrier, the USS Carl Vinson, is heading to waters off Korea in a show of force.

Analysts warn that even failed missile launches provide valuable knowledge to North Korea as it tries to build its weapons program. The country launched a long-range rocket and conducted two nuclear tests last year, including its most powerful to date.

Aside from improving the technology, North Korean missile and nuclear tests are seen by outside analysts partly as efforts to bolster the domestic image of leader Kim Jong Un and apply political pressure on Seoul and Washington.

Kim Jong Un has overseen three nuclear tests and a string of missile and rocket launches since taking over after the death of his father, dictator Kim Jong Il, in late 2011.

Another missile test from Sinpo failed earlier this month, when the rocket spun out of control and plunged into the ocean. That launch came shortly before Trump’s first meeting with Chinese leader Xi Jinping. China is North Korea’s only major ally.

The extended-range Scud missile in that earlier launch suffered an in-flight failure and fell into the sea off North Korea’s east coast, according to U.S. imagery and assessments.

Despite Sunday’s failure, the North’s previous claim to have used “standardized” warheads has led to worries that it was making headway in its push to develop small and sophisticated warheads to be topped on long-range missiles.

Washington sees North Korea’s pursuit of nuclear weapons and ballistic missiles as a threat to world security and to its Asian allies, Japan and South Korea. The United States, South Korea and other countries have vowed to apply more pressure on the North, but so far nothing has worked to stop Pyongyang’s nuclear program.

Six-nation negotiations on dismantling North Korea’s nuclear program in exchange for aid fell apart in early 2009.