Defense Secretary Leon Panetta says the continued exchange of artillery fire between Syria and Turkey raises additional concerns that the conflict may escalate and spread to neighboring countries.
Panetta said the U.S. is using its diplomatic channels to relay worries about the fighting in the hopes that it will not broaden.
His comments during a trip to Peru come on the heels of warnings from Turkey's prime minister that his country is not far from war with Syria.
Turkish and Syria traded artillery fire Saturday as rebels clashed with President Bashar Assad's forces near the border. The clash heightened fears that the crisis could erupt into a regional conflict. Turkish Prime Minister Recep Tayyip Erdogan has warned Damascus that his country won't tolerate such acts.