Soul, South Korea ? North Korea said Wednesday it had reactivated its nuclear facilities, a surprise announcement that raised questions of whether it was trying to take advantage of Washington’s preoccupation with Iraq to ratchet up pressure in its own standoff with the United States.

In Washington, the State Department said that if the announcement was true, “this would be a very serious development.” It demanded the North “reverse this action … North Korea must visibly, verifiably and irreversibly dismantle its nuclear weapons program.”

A North Korean spokesman announced the reactivation, deepening the crisis over Pyongyang’s nuclear ambitions, just before Secretary of State Colin Powell spoke at the U.N. Security Council, presenting the U.S. case against Iraq.

The North said the reactivated facilities would “for the present stage” be used only to produce electricity — but the United States says the facilities can produce nuclear weapons within months.

Even as it presses toward war with Iraq over alleged hidden weapons of mass destruction, the United States has insisted it wants a peaceful solution in its standoff with North Korea.

President Bush “keeps all of his options open” but still believes the standoff can be resolved diplomatically, National Security Adviser Condoleezza Rice said in an appearance on ABC’s “Nightline.”

White House spokesman Ari Fleischer discounted that Pyongyang was timing the issue with Iraq developments.

“North Korea has a history of doing things like they did in the ’90s, outside of the context of Iraq,” he said.

The North’s announcement came hours after South Korea opened a road across the heavily fortified border for the first time in more than half a century, trying to ease tensions with the isolated communist regime.

Pyongyang wants direct talks with Washington. Analysts say North Korea, which often accuses the United States of plotting to invade it, fears Washington will turn up pressure on it if a war against Iraq is successful.

The North may hope that heightening the standoff at a time when Washington is trying to concentrate on Iraq could prompt the United States to make concessions.

The Pentagon is considering bolstering U.S. forces in the region to deter the North from any provocations during an Iraq war. Washington says it has no plans to invade North Korea.

Defense Secretary Donald H. Rumsfeld called North Korea “a terrorist regime” and said restarting the nuclear program would give the North a troubling option — making nuclear weapons for itself or selling them to any other country.

The United States is pressing for the U.N. nuclear watchdog agency to refer the issue to the Security Council — which would likely impose punitive sanctions on the North. Pyongyang vehemently opposes such a move.

At the International Atomic Energy Agency, spokeswoman Melissa Fleming had no immediate comment on the report from the North.

The Vienna-based IAEA’s 35-nation board of governors will meet next Wednesday on the standoff and is almost certain to send the dispute to the Security Council.

The North froze its nuclear facilities in a 1994 agreement with the United States, but the deal unraveled following U.S. revelations in October that North Korea had embarked on a second, clandestine nuclear program.

Washington and its allies suspended oil shipments as punishment. In response, Pyongyang said in December it would revive its nuclear facilities and threw out IAEA monitors, leaving the world unable to observe how the sites are used.

The North Korean spokesman said his country had restarted the nuclear facilities and was “putting (their) operation … for the production of electricity on a normal footing.”

Activity at the facilities will be only for “peaceful purposes, including the production of electricity, at the present stage,” said the unidentified spokesman in remarks carried by the official KCNA news agency.

U.S. officials say the amount of electricity that North Korea can produce at its 5-megawatt nuclear reactor is negligible.

The nuclear complex at Yongbyon, north of Pyongyang, includes a building that stores 8,000 spent fuel rods and a reprocessing laboratory, where the North Koreans can extract weapons-grade plutonium from those fuel rods.

The North Korean spokesman did not refer to specific facilities.

Last week, U.S. officials said spy satellites had detected covered trucks apparently taking on cargo at the fuel rod storage facility. Enough plutonium can be extracted from the spent rods to make four or five nuclear weapons within months, U.S. officials say.

Earlier Wednesday, South Korea opened the first cross-border land route with the North since the peninsula was divided in 1945 and called for more reconciliation efforts.

Ten buses carried 107 South Koreans on the new road to North Korea’s scenic Diamond Mountain resort. The Korean border has been tightly sealed since the 1950-53 Korean War ended without a peace treaty.

South Korea believes expanded exchanges with North Korea can encourage a peaceful resolution to the current nuclear standoff.