The crew members of a U.S. Navy plane held in China have been trained in a delicate art of conversation: not upsetting their captors, yet not telling them too much.

The talent has likely been put to the test. U.S. officials say Chinese authorities have already questioned the crew.

The training is called SERE, for Survival, Evasion, Resistance and Escape.

Those particular skills do not exactly fit the situation facing the 21 men and three women held on the island of Hainan — theirs is not a wartime dash through the jungle.

But U.S. officials say that program should have left the crew well-versed in dealing with the authorities detaining them since the emergency landing of their surveillance plane Sunday.

"There's a code of conduct that they have that I presume that they are following," State Department spokesman Richard Boucher said Thursday.

Speaking in circumspect fashion, he said they are likely adhering to "certain obligations."

The crew has been held in what China calls "protective custody," forbidding further contact with U.S. diplomats since an initial and brief meeting Tuesday.

Generally, they are being housed in pairs, U.S. officials say, but the pilot has been housed alone, perhaps leaving him subject to particularly intense questioning.

Officials say the crew has gone through SERE training, which is standard for service members on such a specialized aircraft.

The training provides information about survival tactics should a plane be downed, how to contact rescue personnel, how to evade capture if necessary and how to deal with captors.

If questioned, the crew is advised to discuss matters that are not classified or sensitive. But they are also instructed not to act in a way that might infuriate interrogators.

"The name, rank, serial number idea is really a wartime thing," said a defense official, speaking on condition of anonymity. "They might just say they were flying at 10,000 feet and they collided with something. Or they might decide to say nothing."

Diplomats who met the crew members Tuesday said they were in good health.

One graduate of military survival training was Air Force Capt. Scott O'Grady. In 1995, he evaded capture and lived off bugs, grass and his wits for six days after his jet was shot down in the mountains of Bosnia-Serb territory.

O'Grady moved around at night to find food and a safe hiding place until he could call in Marine helicopters to rescue him.

Francis Gary Powers, shot down over Russia in 1960 on a spy flight, recalled being interrogated for up to 12 hours a day by his captors.

"I refused to answer several of their questions," he later told Congress. "You shouldn't go overboard with this cooperation, I think."

After parachuting from his U-2, he told Soviet authorities he'd strayed into their air space, but the maps and rubles in his possession gave him away. At that point, he acknowledged working for the CIA.

Powers was convicted of espionage and released after 21 months in a spy swap.

He said he was generally not physically mistreated during his imprisonment.

By contrast, many of the 82 sailors from USS Pueblo spy ship were beaten and humiliated during their 11 months in the hands of North Korean captors in 1968.