BEIRUT — Turkey’s president vowed Monday to keep up the pressure against a U.S.-backed Syrian Kurdish militia after his troops captured the Syrian town of Afrin, threatening to expand the military offensive into other Kurdish-held areas across northern Syria and even into neighboring Iraq.

President Recep Tayyip Erdogan appeared set on forcing Washington to reconsider its partnership with the Syrian Kurdish fighters, the main U.S. ally in the fight against the Islamic State.

Turkey first launched its military operation in Syria in 2016, and Erdogan has repeatedly said it will not allow a “terror corridor” along its border – a reference to territories controlled by the Kurdish forces, which Turkey views as terrorists because of their links to Kurdish insurgents fighting inside Turkey.

Emboldened by Sunday’s capture of Afrin, Erdogan went even further Monday, asserting that Turkish troops and allied Syrian forces would press eastward, targeting territory that includes Kobani, a town that has become a symbol of the fight against the Islamic State militants, as well as Qamishli, where the Syrian government controls an airport and a security zone.

Also in the cross hairs is Manbij, a town jointly patrolled by U.S- and Kurdish forces.