Russian Foreign Minister Sergey Lavrov said about Ukraine's accession to NATO that Moscow "categorically does not accept the appearance of NATO on the Russian borders." He called it "a real red line."

"Even if Ukraine does not join NATO, the appearance there of U.S. strike weapons and military bases on the Sea of Azov is the second red line," he said at a briefing at the department on Friday.

Lavrov echoed Russian Defense Minister Shoigu and said there are "several hundred U.S. and British military personnel in Ukraine."

"The participation of Western instructors in the conflict in Donbas would cross all red lines and mean a direct clash between Russian people and NATO troops," he threatened.

Before this Lavrov said that "Russia's patience has come to an end" and threatened to respond to the refusal to close NATO's doors to Ukraine.