President Donald Trump said Thursday that the United States will be talking to the Democratic People's Republic of Korea (DPRK) "soon," indicating stalled denuclearization negotiations could quickly pick up steam.

Trump's remarks come as negotiators from the two countries are expected to meet in Sweden this weekend to resume working-level talks on denuclearization.

"We'll see," Trump told reporters at the White House. "They want to talk, and we'll be talking to them soon. We'll see."

The DPRK on Thursday claimed that it had successfully test-fired a new submarine-launched ballistic missile (SLBM) from sea to contain external threats and bolster self-defense.

The new type of SLBM called Pukguksong-3 was "fired in vertical mode" in the waters off the eastern city of Wonsan on Wednesday, KCNA said.

DPRK's official newspaper said Friday that the SLBM represents a "grave statement" to hostile forces, calling the weapon a "time bomb" and the "most fearful dagger" for its enemies.

The DPRK chief nuclear negotiator, who arrived in Stockholm on Thursday, voiced "high expectations and optimism" over the upcoming working-level denuclearization talks with Washington.

The U.S. chief negotiator, Stephen Biegun, is also expected to head to the Swedish capital soon.

Preliminary contact is expected on Friday before holding working-level discussions on Saturday, said ROK news agency Yonhap.

Meanwhile, the U.N. Security Council will likely meet behind closed doors on the DPRK issue next week, Reuters said on Thursday quoting diplomats.