The Bush administration has warned Russia's nuclear-weapons chief of plans to let lapse an agreement turning Russian weapons scientists, labs and factories to nondefense work if Moscow fails to expand liability protections for American scientists and corporations.

Nonproliferation advocates in Congress called the move a "dan-gerous and unnecessary development" that is contrary to U.S. security interests in keeping Russian weapons, materials and expertise out of the hands of terrorists.

Six House Democrats urged the White House on Tuesday to reconsider and renew the agreements for another year, saying "Few objectives are as central to U.S. national security as eliminating these threats as soon as possible."

Energy Secretary Spencer Abraham has cautioned Russian Atomic Energy Minister Alexandr Rumyantsev that the United States will not renew the 1998 Nuclear Cities Initiative unless Moscow shields Americans from lawsuits based on premeditated acts that cause injury or death to Russian workers.

Due to expire Sept. 22, the $20 million-a-year Nuclear Cities Initiative has been a perennial target of fiscal conservatives and Cold War-style hawks, who point to its only modest success at diverting unemployed Russian weaponeers and unused nuclear facilities to new jobs.

So far, the program has removed 500,000 square feet from nuclear-weapons assembly work and redirected roughly 400 Russian scientists and engineers to fuel-cell research and the manufacture of artificial limbs.

But those achievements seem meager against the monolith of the Russian nuclear-weapons enterprise of 75,000 workers, of whom an estimated 15,000 to 30,000 are considered unemployed or underemployed.

Since the late 1990s, the Pentagon and Energy Department have run a family of "Cooperative Threat Reduction" programs to prevent the migration of Russian weapons, materials and skills into the black market and the hands of terrorists, driven by wrenching economic adjustments and poverty.

The earliest of these programs required the Russian government to fully indemnify American scientists and corporations against any liability, including from intentional, "premed-itated" acts.

"The Russians are being put in a position where they're being told that even if a U.S. contractor performs a harmful act intentionally that you, Russia, are on the hook," said Raphael Della Ratta, a coordinator at the Russian American Nuclear Security Advisory Council, a non-profit research group in Washington, D.C. "Of course, the Russians don't like that."

The Energy Department has not released Abraham's correspondence with Rumyantsev, but the secretary's staff said he was urging the Russians to allow current Nuclear Cities projects to continue even if the agreement expires. The lapse, however, would not allow any new projects to expand employment of Russian weaponeers.

"Given the concern that a terrorist organization or rogue nation seeking to develop their own nuclear arsenals would actively recruit these scientists, it only makes sense to continue with the very program that helps them transition to peaceful, alternative careers," said Rep. Ellen Tauscher, D-Alamo, who joined fellow Democrats on House Armed Services Committee and the California delegation in writing to President George W. Bush about the agreement.

"A lackluster commitment to stopping the spread of nuclear weapons seems to be a pattern with this administration," she said.

Joe Davis, an Energy Department spokes-man, took issue with Tauscher's characterization, noting that the administration recently concluded a pact with Russia to phase out plutonium-producing nuclear reactors in favor of energy plants powered by fossil fuels.

"We would just like to see some of those workers that the congresswoman represents protected," Davis said.