A motorist rides past a banner for the DPRK-US Hanoi Summit in Hanoi, Vietnam, February 25, 2019.  (Photo: VCG)

Democratic People's Republic of Korea's (DPRK) chief nuclear negotiator on Thursday voiced "high expectations and optimism" over the upcoming working-level denuclearization talks with the United States, on his way to Stockholm for the meeting.

The talks are scheduled on October 5, as DPRK's news agency KCNA reported on Tuesday, while Kim Myong Gil, former DPRK ambassador to Vietnam, is leading a four-member delegation for the work-level talks.

"[We] are heading to working-level negotiations with the U.S," Kim confirmed to reporters at Beijing International Capital Airport, adding that "as the U.S. side sent a new signal, I bear high expectations and optimism, and I am also optimistic about the results."

They were reportedly moved to another terminal that leave for the Swedish capital of Stockholm, according to Yonhap.

China welcomes the resumption of the talks and expects positive outcomes from the dialogue, said Chinese Foreign Ministry on Wednesday

DPRK First Vice Foreign Minister Choe Son Hui earlier said that Pyongyang and Washington agreed to resume talks Saturday following the two sides' "preliminary contact" the previous week.

"The delegates of the DPRK side are ready to enter into the DPRK-U.S. working-level negotiations," Choe said. "It is my expectation that the working-level negotiations would accelerate the positive development of the DPRK-U.S. relations."

The United States confirmed Tuesday that it will resume nuclear talks with the DPRK in a matter of days. "I can confirm that U.S. and DPRK officials plan to meet within the next week," State Department spokeswoman Morgan Ortagus said without further details.

There has been speculation that the meeting could take place in Sweden, where the envoys of the two Koreas and the U.S. held talks in January ahead of the Trump-Kim summit in Vietnam.

According to Yonhap, member of DPRK's delegation including Kwon Jong Gun, former head of the DPRK Foreign Ministry's North American affairs department, and Jong Nam Hyok, a researcher at the DPRK Institute for American Studies under the ministry.

Meanwhile, 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, ahead of fresh nuclear talks.

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.

Shortly after the test, the U.S. State Department called on Pyongyang to "refrain from provocations" and remain committed to nuclear negotiations.

"We call on North Korea (DPRK) to refrain from provocations, abide by their obligations under UN Security Council Resolutions, and remain engaged in substantive and sustained negotiations to do their part to ensure peace and stability on the Korean Peninsula and achieve denuclearization," a U.S. Department of State spokesperson said in Rome.

The upcoming talks will mark the first nuclear negotiations between the two sides since the Hanoi Summit between U.S. President Donald Trump and DPRK leader Kim Jong Un. The meeting broke down without a deal due to differences on denuclearization measures and sanction relief.