Vladivostok, Russia ? Russian, U.S. and British forces were scrambling to rescue seven Russian sailors trapped with dwindling oxygen supplies 600 feet under the Pacific on a mini-submarine caught on an underwater antenna.

The commander of the Russian Pacific Fleet, Adm. Viktor Fyodorov, said rescuers were hoping to tow the AS-28 naval sub into shallower waters off the Kamchatka Peninsula and send divers down to the crewmen who have been trapped in it for two days at a depth of 600 feet. A British military plane and a U.S. Air Force jet carrying remote-controlled underwater robots took off for the disaster scene in Russia’s Far East, north of Japan.

Moscow asked for outside assistance within hours of news breaking about the sub’s plight – a speedy request that was a marked change since the Kursk nuclear submarine disaster in 2000, when Russian officials waited until hope was all but exhausted. All 118 died aboard the Kursk.

The vessel became stuck on Thursday, and was the subject of desperate rescue efforts and widely varying estimates of how much oxygen remained on board.

Navy crews load rescue equipment onto a C-5 transport plane Friday at NAS Coronado in Coronado, Calif. The Navy is sending Remote Operating Vehicles to help rescue a Russian mini-submarine that is stranded in the Northern Pacific.

Both the U.S. and British rescue teams could reach the site off the Kamchatka Peninsula in time – if earlier estimates that there was enough oxygen to keep the seven alive for 24 hours held true. Fyodorov said early today that there was oxygen for “at least 18 hours,” a distinctly less optimistic statement than his earlier assertion that the air would last into Monday.

“The situation is not simple. I don’t want to overdramatize the situation, but also at the same time, I don’t want to say it is absolutely, so to speak, easy and momentarily resolvable,” Fyodorov said in comments televised on NTV.

The confusion over the air supply darkly echoed the sinking of the Kursk almost exactly five years ago. That disaster shocked Russians and deeply embarrassed the country by demonstrating how Russia’s once-mighty navy had deteriorated as funding dried up following the 1991 Soviet collapse.

The new crisis is also highly embarrassing for Russia, which will hold an unprecedented joint military exercise with China later this month, including the use of submarines to settle an imaginary conflict in a foreign land. In the exercise, Russia is to field a naval squadron and 17 long-haul aircraft.

The rescue effort underscores that promises by President Vladimir Putin to improve the navy’s equipment have apparently had little effect. Authorities initially said a mini-sub would be sent to try to aid the stranded one, but the navy later said it was not equipped to go that deep.

Putin was criticized for his slow response to the Kursk crisis and reluctance to accept foreign assistance. By late Friday, Putin had made no public comment on the latest sinking.