South Korea’s military on Wednesday stated that North Korea had carried out a ballistic missile test involving a submarine. The missile was launched one day after North Korean state media announced that Pyongyang and Washington will be holding working-level negotiations on October 5, after a first meeting on October 4.

Reuters stated that the launching of a ballistic missile from a submarine “would be the most provocative test by North Korea since it started the talks with the United States in 2018.” A spokesperson for the US State Department urged the North Korean regime to “refrain from provocations.”

North Korean leader Kim Jung-un met with US President Donald Trump in the Demilitarized Zone (DMZ) between North and South Korea earlier this year. During that meeting, both leaders agreed to a new round of talks on North Korea’s nuclear program, but the prospects that such talks would actually materialize seemed slim in the past few months, with North Korea repeatedly slamming US sanctions and carrying out a variety of missile tests.

Read more: North Korea fires ballistic missile, possibly from submarine, days before talks