Pompeo: S-300 delivery to Syria a 'very serious escalation'

US Secretary of State Mike Pompeo says the Russian delivery of the S-300 air defense system is a “very serious escalation,” but refuses to say if the US will respond to the move.

“Having the Russians deliver the S-300 into Syria presents greater risk to all of those in the affected areas, and to stability in the Middle East,” he tells reporters. “We consider this a very serious escalation.”