SEOUL, South Korea — A meeting Wednesday of the rival Koreas’ nuclear envoys could provide crucial momentum toward restarting disarmament talks, just months after the two countries were threatening to bomb each other into rubble.

Relations are still complicated and wariness lingers as the envoys prepare for face-to-face talks in Beijing that aim to build on their surprise meeting in July — which was seen as a small breakthrough after months of acrimony.

But there has been a recent flurry of diplomatic and cultural exchanges between the Koreas. South Korea’s hard-line government is making public vows of a new flexible approach to Pyongyang, and the North’s state media have eased harsh rhetoric aimed at Seoul’s leaders.

Energy officials from the Koreas and Russia are conducting separate preliminary discussions on an ambitious plan to pipe Siberian natural gas through cash-starved North Korea to energy-hungry South Korea.

“Generally, there was a mood of optimism at the possible resumption of the talks,” said Georgy Toloraya, a regional director for Russkiy Mir Foundation in Moscow, who sat in on closed-door discussions with the North Korean nuclear envoy, Ri Yong Ho, at a seminar Monday in Beijing.

Skeptics see North Korea’s moves as a disingenuous “charm offensive” meant to extract aid and strengthen the government as leader Kim Jong Il works to secure a smooth transition of power to his twenty-something son.

The goal of all the diplomatic wrangling is to rid North Korea of its nuclear weapons programs. But first there must be a return to six-nation disarmament talks that have been stalled since the North walked out in early 2009.

North Korea has pushed for months to restart the talks, but South Korea and the U.S. have been wary, saying Pyongyang must first abide by earlier nuclear commitments.

South Korean and U.S. officials want North Korea to halt its uranium-enrichment program, freeze nuclear and missile tests and allow international nuclear inspectors back into the country before the international talks resume.

“We are neither pessimistic nor optimistic” about the prospect for this week’s meeting in Beijing, South Korean Foreign Minister Kim Sung-hwan told lawmakers Monday.

Washington also insists that ties between the two Koreas must improve, which puts a lot of focus on any progress in Wednesday’s talks.

The overall relationship between the Koreas is still at a low point. The Koreas have been in a bitter, near-constant standoff since the 2008 inauguration of conservative President Lee Myung-bak, who linked large-scale South Korean aid to North Korea’s progress in nuclear disarmament.

Once-promising joint tours between the Koreas, for instance, have become a sore point.

The tours to the North’s scenic Diamond Mountain halted in 2008 amid tensions surrounding the shooting of a southern tourist by a North Korean soldier. The South has since seized the North’s property at the resort and opened it to international investors. South Korea is asking foreign governments to boycott.

Animosity reached a high point last year when attacks blamed on the North killed 50 South Koreans and sparked threats of war.

The atmosphere improved markedly in July when the Koreas’ nuclear envoys met on the sidelines of a regional security conference and promised to work toward a resumption of nuclear talks. That was quickly followed by meetings in the United States between a senior North Korean official and his U.S. counterparts.

Wednesday’s talks in Beijing between North Korea’s Ri and South Korea’s Wi Sung-lac are being described as a follow-up to the nuclear envoys’ July discussions.

Ri, in Beijing ahead of his meeting with Wi, said the North recently proposed a fresh round of one-on-one talks with the United States, Yonhap news agency reported Monday, citing unidentified people who attended the closed-door forum.

Analysts see Wednesday’s talks as a stepping stone to another round of talks between Washington and Pyongyang.

If U.S.-North Korean talks produce some concessions on both sides, the six-nation nuclear talks could resume by the end of this year, said Yang Moo-jin, a professor at the University of North Korean Studies in Seoul.

Other recent positive signs between the Koreas include a delegation of Buddhists who visited North Korea earlier this month, and Seoul’s approval Monday of a trip this week by Catholic, Protestant and Buddhist leaders to the North.

A prominent South Korean maestro said last week after a trip to North Korea that he has agreed with North Korean officials on regular joint symphony performances in Seoul and Pyongyang — though South Korean officials have yet to review the details.

Many analysts remain skeptical, however, noting that North Korea is still building nuclear weapons.

“North Korea’s quest for food aid and economic benefits will moderate the regime’s behavior for the near-term,” Bruce Klingner, a Northeast Asia specialist at The Heritage Foundation, a conservative Washington think tank, wrote recently. “But make no mistake about it; a failure to achieve those objectives will lead Pyongyang to again calculate the benefits of provocative actions.”