German Foreign Minister Frank-Walter Steinmeier “and I agreed that continued military support for the regime by Russia or any other country risks the possibility of attracting more extremists and entrenching Assad and hinders the way for resolution,” Kerry told reporters after a meeting with his German counterpart.

Washington has been concerned over reports of a Russian military build-up in Syria as a boost to President Bashar al-Assad.

Moscow however argues that any military backing falls in line with existing defence contracts, although reports have surfaced of secret deployments to the country where Moscow has a Soviet-era naval facility.

Russian President Vladimir Putin’s spokesman said Friday that Moscow would consider any request for troops from Assad.