The United States believes the Russian warplane that was shot down on Tuesday by Turkey near the border with Syria entered Turkish airspace for only several “seconds.”
A US official, who spoke on condition of anonymity, said the preliminary assessment was based on detection of the heat signature of the jet by infrared sensors.
The US official told Reuters that the United States was still investigating the incident.
On Tuesday, NATO member Turkey shot down a Russian fighter jet, claiming the aircraft had repeatedly violated its air space.
Turkey said two Russian SU-24 attack planes approached Turkish airspace and that they crossed into Turkish airspace for 17 seconds.
Russian President Vladimir Putin said the jet had been attacked when it was 1 kilometer (0.6 m) inside Syria.
Putin warned of "serious consequences" and said the downing of the Russian plane was a “stab in the back” administered by "the accomplices of terrorists."
Russia has been conducting airstrikes against Daesh (ISIL) and other terrorist groups inside Syria at the request of the Syrian government since September 30.
The United States and its regional allies - especially Qatar, Saudi Arabia and Turkey - have been supporting the militants operating inside Syria since the beginning of the country’s crisis in March 2011.
US President Barack Obama expressed his support for Ankara following the incident and suggested Russia’s air campaign against so-called moderate militants in Syria is contributing to such confrontations.
"Turkey, like every country, has a right to defend its territory and its airspace," Obama said on Tuesday at the White House during joint press conference with visiting French President Francois Hollande.
“I do think that this points to an ongoing problem with the Russian operations,” Obama said. “In the sense that they are operating very close to a Turkish border and they are going after moderate opposition.”