DAMASCUS, Syria — Proclaiming the Syrian people winners in a “dirty war” waged by outsiders, President Bashar Assad was sworn in today, marking the start of his third seven-year term in office amid a bloody civil war that has ravaged the Arab country.

Looking confident and self-assured, occasionally making jokes, Assad declared victory over “terrorism” and said countries that supported the Syrian opposition “will pay a high price.”

The grandiose ceremony at the presidential palace in Damascus caps what has been a recent reversal of fortune on the battlefield for Assad’s forces battling the rebellion against him. In the past year, the 48-year-old leader has managed to seize the momentum in the civil war, with his troops making steady advances on several fronts against outgunned rebels bogged down in infighting.

He won 88.7 percent of the ballots cast in the first multi-candidate elections in decades. The voting didn’t take place in opposition-held areas of Syria, effectively excluding millions of people from the vote.

Syria’s civil war, now in its fourth year, has killed more than 170,000 people and displaced one third of the country’s population.