PIRMASENS, WEST GERMANY, MARCH 8 -- The U.S. Army disclosed new details today of its plans for removing about 400 tons of lethal nerve gas from West Germany by the end of the year in a withdrawal that will leave the United States without any chemical weapons in Europe for the first time in more than 20 years.

The removal, two years ahead of schedule, is expected to provide a boost to West German Chancelor Helmut Kohl, who faces a tough election in December, with voters strongly opposed to chemical weapons on German soil.

"Who would have thought it possible that we would be standing before you today able to say, 'No more chemical munitions in Germany,' " said U.S. Brig. Gen. Dennis L. Benchoff at a press conference hosted jointly by the U.S. and West German armies.

The United States had been so secretive about the nerve gas that this week's announcement marked the first public acknowledgement that the weapons were stored in a large, secluded depot at Clausen, near the French border in the state of Rhineland-Palatinate. "We're speaking of things that only a few days ago were classified as forbidden to be discussed in public," said Benchoff, commander of the brigade responsible for the nerve gas.

In an announcement in Bonn on Wednesday, West German Defense Minister Gerhard Stoltenberg portrayed the withdrawal as a victory for Kohl's center-right coalition and insisted the operation could be carried out safely.

The weapons have long been a source of discontent among many Germans, who periodically staged protests at military installations where the gas was rumored, generally incorrectly, to be stored.

The chemical weapons consist of two types of nerve gas, Sarin and VX, housed in about 100,000 artillery projectiles. According to the complex plan outlined by officials, the shells will be placed in vapor-proof containers, trucked in high-security convoys 28 miles to a railhead at Miesau, taken by train several hundred miles to the North Sea port of Nordenham, and then shipped to Johnston Island in the Pacific for destruction at a U.S. military installation. The removal is expected to begin in July and last one to four months, officials said.

The initial U.S.-German plan called for withdrawal of the weapons by 1992, but Kohl successfully pressed the Bush administration last spring to move more quickly.

The accelerated withdrawal plan met with some resistance from Pentagon officials, who cited safety concerns over moving the gas before equipment and facilities were adequately developed. But Army officials say they have developed "the safest, most comprehensible plan imaginable."

The nerve gas cannot be brought back to Germany without the concurrence of the country's government, which is seen as unlikely in any situation short of war. Nonetheless, the weapons now in Germany represent only 1 percent of the American stockpile. And despite President Bush's call "to rid the earth of this scourge" in a speech to the United Nations last September, the Pentagon is producing a new type of "binary" chemical weapon.

Removal of the arsenal at Clausen will be carried out by American soldiers, but the operation falls under German legal jurisdiction. Spokesmen said the United States will pay about $50 million of the bill for the operation and the Germans about $23 million.

Officials from both countries said they were taking extraordinary precautions to ensure against disaster during movement of the gases. "We have a probability of nil for an accident," said Lt. Col. Gunther Kreibohm, a German officer involved in the operation.

But the promises of safety met with skepticism from Germans attending the presentation here. "If somebody tells me there's no risk, I get concerned," said Dieter Meissmer, a writer for a German scientific journal.