North Korea fired what appears to be a submarine-launched ballistic missile (SLBM) toward the East Sea on Tuesday, South Korea's military said.

The missile was launched eastward from a site in the vicinity of Sinpo, South Hamgyong Province, according to the Joint Chiefs of Staff (JCS). It said the launch was detected at 10:17 a.m. but gave no other details.

"The intelligence authorities of South Korea and the United States are currently conducting a thorough analysis regarding additional details on the missile," the JCS said in a text message sent to reporters.

The North's latest missile test marks its eighth known projectile launch this year. It previously fired a new hypersonic missile, called the Hwasong-8, on Sept. 28.

Sinpo is where North Korea has been pushing to build a 3,000-ton submarine capable of carrying a submarine-launched ballistic missile.

The North previously conducted an SLBM test in 2015 and 2019. The South's military believes that it used a barge rather than a submarine platform during the past tests.

The launch came as the top nuclear envoys of the South, the US and Japan are in Washington to discuss joint efforts to bring the North back to dialogue through humanitarian aid and other incentives.

Pyongyang's continued saber-rattling tempered cautious optimism that has emerged since the reactivation of inter-Korean communication channels earlier this month.

In Washington on Tuesday, Seoul's top nuclear envoy, Noh Kyu-duk, and his US and Japanese counterparts, Sung Kim and Takehiro Funakoshi, plan to meet trilaterally to discuss a joint strategy on the North.

On Monday, Noh and Kim met bilaterally and discussed President Moon Jae-in's recent proposal for the declaration of a formal end to the 1950-53 Korean War, which Seoul believes is an effective measure to build confidence with Pyongyang.

 The US envoy plans to visit Seoul later this week to further discuss diplomacy toward the North. (Yonhap)