MOSCOW (Reuters) - The downing of a Syrian government warplane by the United States is a step toward a dangerous escalation, and Moscow is warning Washington not to use force against Syrian government troops, a senior Russian diplomat told Interfax news agency on Monday.

Russian Deputy Foreign Minister Sergei Ryabkov also told the agency that a set of new U.S. sanctions that can be imposed on Russia will lead Moscow to retaliate.

Ryabkov said that he and U.S. Undersecretary of State Thomas Shannon would meet in St Petersburg on June 23 to discuss problems in bilateral ties, Interfax reported.