Seoul, South Korea ? South Korea won a promise from Russia on Sunday to press North Korea over its nuclear program, as Seoul prepared to unveil to the United States new proposals aimed at defusing the crisis with its communist neighbor.

As the South launched a diplomatic blitz, the North opened the door to possible mediation — though it said it would heighten its combat readiness and denounced the United States.

In Moscow — one of the isolated North’s few allies — South Korean Deputy Foreign Minister Kim Hang-kyung met with his Russian counterpart, Alexander Losyukov.

Losyukov said after the talks that Moscow and Seoul “agreed to make joint efforts to ease the crisis” and persuade the parties to sit down for talks, though he stopped short of promising Russian mediation.

“The slide to unacceptable actions must be stopped,” Losyukov was quoted as saying by the Russian news agency Interfax. “Obviously, our contacts with North Korean colleagues will be intensified.”

A separate team of South Korean diplomats also was expected to present a compromise solution today and Tuesday to the United States and Japan, when the three allies meet in Washington to chart a joint strategy on North Korea. Seoul said it will send a top presidential envoy to the United States for more talks later this week.

No details have been disclosed on the South’s proposals, but it is expected to involve North Korean concessions on nuclear weapons in exchange for security guarantees.

The current standoff began when North Korea announced last month that it was reviving its main nuclear complex, frozen since a 1994 deal with the United States, and forced out international inspectors at the site. Experts believe the complex can be used to produce several nuclear weapons within months.

The International Atomic Energy Agency’s 35-nation board of governors planned to hold an emergency session today to review the nuclear crisis.

A senior nuclear agency official told The Associated Press on condition of anonymity that the IAEA almost certainly would refer the dispute to the U.N. Security Council later today — a move that could lead to punitive sanctions or other actions against the reclusive nation’s regime.

North Korea’s top military brass vowed in a meeting in the capital, Pyongyang, on Saturday to increase the communist army’s combat readiness. A separate statement from the official Korean Central News Agency accused the United States of trying to disarm the North and called the United States the “main obstacle” of Korean reunification.

But North Korea left open the possibility of other countries mediating the dispute — an apparent nod to Seoul’s diplomatic attempts.