NATO has urged Russia to end air strikes “on the Syrian opposition (ISIS) and civilians”, days after Moscow began raids to support Syria’s government.
Moscow says it is targeting Islamic State and other Islamist positions, but US-led allies and Turkey say government opponents are targeted.
Turkish F-16 fighter jets were scrambled after a Russian plane entered Turkey’s air space on Saturday.
NATO said Russia’s actions “have reached a more dangerous level”.
Russia said the incident was a “navigational error”. The US said Turkey would have been within its rights to shoot the jets down.
Saturday’s interception took place near Yayladagi in the southern Hatay region, Turkey says. The foreign ministry in Ankara said it had summoned the Russian ambassador to issue a “strong protest”.
Turkish jets patrolling the border were also “harassed” by an unidentified plane on Sunday, Turkey said.
A statement by Nato’s 28 members, that include Turkey, warned of “the extreme danger of such irresponsible behaviour” and urged Russia “to cease and desist”.