BEIRUT — Five months of multisided clashes in Syria’s crowded northern battlefield have displaced some 66,000 people, a U.N. humanitarian agency said Sunday, a day after the U.S. bolstered Kurdish-led forces with a deployment of armored vehicles amid preparations for a push toward the Islamic State group’s de facto capital.

Besides the autonomous Kurdish-led forces, Turkish, Syrian government and Syrian opposition fighters have all been jostling for territory formerly held by the Islamic State group near the Turkish-Syrian frontier.

The U.S.-backed Syrian Democratic Forces, led by the Syrian Kurdish PKK party, are the current front-runners in the race to Raqqa, the ISIS capital. They are now stationed 5 miles north of the Euphrates River city and supported by U.S.-led coalition airstrikes and a deployment of some 500 U.S. Special Forces operators. The Pentagon has said they are working in an advisory capacity.

The U.N.’s OCHA agency said that the Turkish and Syrian opposition campaign to capture al-Bab from ISIS militants displaced 40,000 residents. They captured the town on Feb. 23, after starting operations in November.

The office said another 26,000 residents have been displaced in fighting around Manbij, held by Kurdish-led forces, and al-Khafseh, held by IS militants. Al-Khafseh is home to the main water station for Aleppo, Syria’s largest city.