US-led campaign not affected by downing of Russian plane: Pentagon

The Pentagon said on Tuesday that the US-led campaign against the extremist group Islamic State was neither affected by nor involved in Turkey's downing of a Russian plane.

"This is an incident between the Russian and the Turkish governments. It is not an issue that involves the Combined Joint Task Force or Operation Inherent Resolve," said Steve Warren, a spokesman for the US-led military campaign against the IS.

"Our combat operations against IS continue as planned and we are striking both Iraq and Syria," said Warren at a Pentagon briefing.

Earlier on Tuesday, a Russian Su-24 crashed in Syria "allegedly because of gunfire from the ground," said the Russian defence ministry.

According to the Turkish military, the Su-24 had been warned 10 times in five minutes about its violation of Turkish airspace, before two Turkish F-16 jets "interfered".

But Moscow said the plane was shot down in Syria's territory.