The top nuclear envoys of South Korea, the United States and Japan were set to hold trilateral talks in Tokyo on Tuesday about efforts to resume dialogue with North Korea, amid renewed tensions over the recalcitrant regime's recent missile launches.

The talks between Seoul's nuclear negotiator, Noh Kyu-duk and his US and Japanese counterparts, Sung Kim and Takehiro Funakoshi, respectively, come after the North test-fired a new type of long-range cruise missile over the weekend amid signs of its reactivation of a plutonium-producing nuclear reactor.

The three are expected to discuss humanitarian support and other incentives to encourage the North's return to dialogue, as it struggles with a series of economic and other hardships exacerbated by pandemic-driven border closures.

South Korea and the US have been discussing humanitarian aid for the North in certain areas, including public health, sanitation and clean drinking water. Before his departure for Tokyo, Noh took note of "considerable progress" in consultations between the allies over such humanitarian support.

In recent months, Seoul has been revving up diplomacy to reengage with Pyongyang, seeking to tamp down lingering skepticism over a peace drive overshadowed by the reclusive state's continued pursuit of nuclear and missile programs.

The International Atomic Energy Agency has recently reported indications of the North resuming the operation of a five-megawatt nuclear reactor at its main Yongbyon complex, including the discharge of cooling water from the reactor.

Noh, Kim and Funakoshi last held their three-way talks in Seoul in June. Last month alone, Noh and Kim held face-to-face talks in Seoul and Washington -- a sign of beefed-up cooperation among the countries over the North Korean issue.

Nuclear talks between Washington and Pyongyang have remained stalled since the Hanoi summit in 2019 between then-US President Donald Trump and North Korean leader Kim Jong-un ended without a deal. (Yonhap)