My plane lands in Xiamen then I get on another plane and go to Thailand. Do I need a China Visa?

Dear Sir,
I live in the USA, Do I need a China entry permit to get on a connecting flight in Xiamen? I fly from Los Angeles to Xiamen I get off the plane and then I board another plane and fly to Thailand? I will stay in the airport for 4 hours before getting on the second plane to fly to Thailand. Do I need a China entry permit to get on the second plane in Xiamen? Thank you for helping me.