A North Korean fighter jet crashed Wednesday on what appeared to be an illicit flight deep inside China, South Korean and Chinese news agencies reported.

The South’s Yonhap news agency, reporting from the major northeastern Chinese city of Shenyang, said the pilot, the only person on board the plane, was killed in what intelligence sources believe was an attempt to defect to Russia. A house reportedly was destroyed in the crash but no one on the ground was injured.

Photographs of the crash site clearly show the North Korean red star symbol on the fuselage beneath the tail section. South Korean defense officials believe the plane was a MiG21, a fairly advanced model. The North Korean Air Force has about 700 planes, ranging from MiG15s used in the Korean War to late-model MiG23s and a few MiG27s. The former Soviet Union provided most of the planes before the collapse of Soviet rule 20 years ago.

China’s Xinhua news agency confirmed the plane had gone down in the district of Fushun in Liaoning Province, about 120 miles north of a North Korean air base at Uiju near the Yalu River border. Security officials reportedly swarmed to the crash scene and blockaded the area but not before locals photographed the wreckage and spread the pictures on the Internet.

The plane took off from Uiju, according to South Korean radar images. South Korean defense officials said the plane was a MiG21, not an early model MiG15 used as a trainer, based on information picked up by monitoring equipment they said is able not only to track the plane but also to identify the model.

Analysts believe the plane may have been bound for Russia and flown off course, but the reason for the flight or the crash remains shrouded in mystery. The inexperience of the pilot, or fuel shortage though, may have been a factor.

Bolstering that theory, analysts say North Korean pilots often lack adequate training due to scant fuel available to fly as many hours as needed to hone their skills.

“Most of their planes are out of date,” says Kim Tae-woo, senior research fellow at the Korea Institute for Defense Analyses. ”They fly very much less than our South Korean planes. They have a fuel problem and lack spare parts.”

The only advantage the North Koreans may have, says Mr. Kim, is in sheer numbers. South Korea has about 500 planes, spearheaded by about 60 F-15s and many more F-16s. The difference, he says, is “we have well trained pilots, and we have fuel.”

While citizen defections are becoming increasingly common and North Korean soldiers have defected from time to time into China due to food shortages, pilot defections are extremely rare.

Three North Korean pilots have defected to South Korea, but there is no record of a North Korean pilot defecting to Russia. The pilot in this case may have believed that he could quickly overfly China, which would automatically have returned him to certain execution in North Korea.

The last time a North Korean pilot reportedly defected was in May 1996, when he flew a MiG19 to the South Korean air base at Suwon, south of Seoul. A North Korean pilot took advantage of a training exercise in February 1983 to fly a MiG19 to another base near Seoul. And a pilot flew a MiG15 to South Korea in September 1953, just two months after the end of the Korean War.