BEIRUT – Syria's rebels stepped up attacks on strategic sites including a sprawling military complex in the country's north on Friday, while reports emerged that President Bashar Assad's forces continued to fire Scud missiles at rebel areas.

Russian President Vladimir Putin told European leaders that Russia does not seek to protect Assad but that only a negotiated solution can end the conflict – an outcome that looks unlikely as rebels make gains across the country.

While few observers expect Syria's 21-month-old conflict to end soon, most say steady rebel advances appear to be tipping the balance in favor of those fighting to topple Assad's regime.