Here are 3 times passenger planes have been shot down on accident amid heightened military tensions

Iran Air Flight 665 was traveling from Tehran to Dubai when it was shot down over the Persian Gulf on July 3 1988 by a surface-to-air missile fired by the US Navy missile cruiser USS Vincennes.

All 290 passengers were killed.

At the time of the shoot-down, the situation in the Gulf was tense, as the US Navy had exchanged gunfire with Iranian boats and even lost assets at the hands of the Iranians, who had been mining strategic waterways.

The US insists that the crew of the cruiser misidentified the aircraft as a possible enemy F-14 Tomcat. The US says the Navy made 11 unanswered radio calls before opening fire. Iran argues the aircraft identified itself as civilian. The black box was never recovered.

The incident continues to be a sore point in an already strained relationship between the US and Iran.

Korean Air Lines Flight 007 was flying from New York City to Seoul when it diverted from its original course and entered Soviet airspace. The aircraft was shot down by a Soviet Su-15 fighter jet on September 1, 1983.

All 269 people on board lost their lives.

The tragic incident occurred during a period of high Cold War tensions, and the Soviets said they mistook the aircraft for a US surveillance aircraft, such as one of the US RC-135 reconnaissance aircraft in the area.

The pilot of the Soviet interceptor told CNN several years ago he signaled the aircraft and fired warning shots without response. There were reportedly no attempts, though, to contact the passenger aircraft over the radio. The details of what exactly happened to this flight remain unclear.

"My orders were to destroy the intruder. I fulfilled my mission," the pilot said.