BONN, JULY 26 -- Operation Lindworm, the removal of once secret stockpiles of U.S. chemical weapons from West Germany, began the first leg of its delicate road, rail and sea journey today to a remote Pacific Ocean destruction plant.

Starting at Clausen in southwestern Germany, a convoy of 80 trucks and vans -- 20 of them packed with vapor-proof steel containers full of enough nerve gas to wipe out the Earth's population three times over -- snaked 30 miles through densely populated German towns and along a closed autobahn to a rail depot.

There were no incidents along the route, and only a few demonstrators protested the operation.

The U.S. Army, which has stored the gas in West Germany for 23 years but only admitted its presence in 1983, has been planning the move for four years. The removal was originally to have begun in 1992 but was moved up after environmental groups pressured Chancellor Helmut Kohl, who in turn pushed the United States for a speedier timetable.

The Army and German officials said that every possible precaution had been taken to ensure safe transport of the gas -- including helicopter surveillance, strategically placed sharpshooters and an escort of 1,500 police officers -- and that only a terrorist attack or fire could spark a disaster.

But some West German environmentalists remained unconvinced; their lawsuit to stop the transport was turned aside earlier this week.

Today's load is far more volatile than more modern chemical weapons, because the 100,000 Sarin and VX nerve-gas artillery shells in the shipment contain chemicals that have already been mixed, making them subject to explosion even from a slight crack in a shell casing. In more recently developed chemical weapons, the dangerous elements are kept separated until a shell is fired.

The U.S. soldiers accompanying the convoy wore survival kits strapped to their thighs. By pressing on the kit, a soldier who comes into contact with the poison gas could inject himself immediately with two antidotes.

Sarin and VX, which paralyze the respiratory system and distort nerve impulses, were designed to kill within minutes by inhalation or within two hours by skin absorbtion. Sarin, 10 times as toxic as any previous chemical weapon, was invented by the Germans in 1938. VX is a descendant of Sarin.

The nerve agents' final destination is Johnston Island, 700 miles south of Hawaii. There, they are to be destroyed at the first of an expected eight or nine facilities that together are to cost $3.8 billion.

The Greens, West Germany's small but influential environmentally oriented party, called the $73-million transport "a hurried and secretive operation" with "severe security failings." Of the 100,000 shells, 65 have rust or scratches on them and have been specially packed in sealed containers. A spokesman for the 59th Ordnance Brigade said Army tests have shown that even light anti-tank missiles could not penetrate the layers of steel surrounding the gas shells.

The Greens joined residents of villages through which the weapons are moving in the lawsuit, which sought public hearings and studies of the risks of moving the chemical arms through populated areas.

The Bonn government answered critics of the transport plan by saying it had to submit to American dictates on moving the gas. But a U.S. document obtained by the West German newspaper Die Tageszeitung says that "the overall control over the preparation and the removal of C-weapons from West Germany lies with the West German authorities."

The mayor of Clausen, Berthold Schaefer, endorsed the quick removal of the gas from his town, saying that local fears were a result of "panic being spread merely by the media."

The United States is believed to have about 25,000 tons of poison gas; the Soviet Union is estimated to have up to twice as much. President Bush and Soviet President Mikhail Gorbachev agreed at their Washington summit last month to cut each country's supply to 5,000 tons in the next 12 years.

It will take 30 days for repeated convoys to move all 437 tons of gas to the rail depot at Miesau. The rail portion of the trip, which will last a week, will take the weapons to the North Sea port of Nordenham, where the cargo will be loaded onto two U.S. Navy ships for the final leg.