ALGHOOZ, Syria — The arc of Omar Abdulkader’s transformation from farmer to fighter resembles that of uncountable others in Syria, where since 2011 tens of thousands of men have been drawn into a civil war.

A rebel commander seeking to overthrow President Bashar al-Assad, he described the choice of a cornered man. His resistance began with peaceful demonstrations, he said. When the government answered with force, his tactics changed. “It was only after they showed that they would kill us that we became armed,” he said.

But there is a difference between this story and many others. Mr. Abdulkader is a Kurd, not an Arab, which means his experiences and decisions upend conventional wisdom that holds that the Kurds do not see this as their fight.

To hear the governments of Turkey and Syria describe it, Syria’s Kurds often side with or remain neutral toward Mr. Assad, whose government supported the Kurdistan Workers’ Party, or P.K.K., in its bloody insurgency against Turkey until 1998, when Syria grudgingly extradited the Kurdish group’s leader at the brink of war with Turkey.