A Russian mini-submarine used in rescue operations itself became the center of an intense international rescue effort Friday after getting caught in a fishing net on the Pacific Ocean floor with no more than a day's supply of breathable air for its seven-man crew.

As part of the rescue effort, the U.S. military was rushing two remote-control underwater vehicles by air Friday from San Diego to waters off the southeastern tip of the Kamchatka peninsula where the submarine is trapped more than 600 feet down.

"It's very much an urgent situation," said Lt. Cmdr. Lisa Brackenbury, a Navy spokeswoman. The flight to Petropavlovsk, a port city in Russia, was scheduled to take about 12 hours, and Russian trucks were waiting to immediately carry the Super Scorpio rescue craft, unmanned remote operated vehicles, to a ship that would transport them to seas over the AS-28 sub, Navy officials said.

It was unclear whether the U.S. operation and simultaneous Russian efforts to save the crew would succeed. "There is air remaining on the underwater apparatus for a day -- one day," said Capt. Igor Dygalo, a spokesman for the Russian navy.

The AS-28 is part of the navy but is unarmed and normally used in underwater rescue operations.

The accident occurred Thursday during a combat training exercise when the propeller of the craft got snared in fishing nets, according to Russian naval officials. The craft became further entangled when it applied maximum power in an attempt to free the propeller, a maneuver that exhausted some of its air supply, officials said.

Russian naval officials said they had been able to establish contact with the sailors on board, and though all of them were alive, they were too far down to swim to the surface.

Russia's quick call for foreign help stood in marked contrast to its delays five years earlier, when the Kursk nuclear submarine sank after an onboard explosion during training exercises in the Barents Sea. Many of the 118 seamen on board perished immediately, but at least 23 sailors on board survived for hours as their air supply dwindled.

The secretive and botched operation to rescue the Kursk's crew outraged the sailors' families and the Russian public. This time, military officials here turned quickly to the United States, Britain and Japan for help.

Britain is also sending a Scorpio to the area and Japan has dispatched three ships to help, officials from the two countries said.

The commander of Russia's Pacific Fleet, Adm. Viktor Fyodorov, said the rescue might well take place before the arrival of any international help, which he nonetheless welcomed.

"We will carry out this task by using our own resources, and will raise it to the surface," Fyodorov said. "While we have so far been taking rescue measures piecemeal, we will start a comprehensive operation within hours."

He later told Russia's NTV television that a Russian ship had snagged the submarine with a cable and was trying to drag it to shallower water.

The C-5 transport plane carrying the American rescue team will be the first U.S. military aircraft since World War II to fly into the region, which has numerous closed military sectors.

It was carrying two Super Scorpios. The eight-foot-long vessels can reach a depth of 5,000 feet and are equipped with lights, video cameras, two arms capable of lifting 250 lbs each, and a cutter able to sever inch-thick steel cables.

"They're looking to be able to release the propeller from whatever it's caught on, whether fishing line or cable. That will be the first priority," said a U.S. Navy official, who spoke on background because of the uncertainty of the problem. "Then they can use their ballast to surface." About 30 Navy personnel, including the vehicle operators, deep-sea divers, technicians and a doctor, flew with the equipment toward Petropavlovsk. The divers are equipped with suits that allow them to reach depths of 2,000 feet for up to six hours. Two more diving suits and a deep-sea drone are being dispatched by the U.S. Navy from the East Coast.

"We're trying to offer multiple tools for the tool box," Brackenbury said.

Cooperation between the Russian and U.S. navies on the rescue effort has been good, Brackenbury said, noting that the two forces conducted a four-week submarine rescue exercise in June off the coast of Italy. It was the first time that Russian units took part in a submarine rescue exercise with NATO.

Also helping to coordinate the rescue is the International Submarine Escape and Rescue Liaison Office, a NATO initiative set up in Norfolk in the fall of 2004.

The rush to dispatch U.S. personnel and equipment was in keeping with a "brotherhood of the sea" rule that overrides national differences, one official said. "That's why we're taking this so seriously. It's very important to us to get to these folks."

Tyson reported from Washington.