U.S. military officials in Afghanistan say a soldier who has been missing since Tuesday is now believed to have been captured by insurgents.

Military spokeswoman Captain Elizabeth Mathias declined to provide details on the soldier's identity or the circumstances of his apparent capture.  She said the military is withholding information for his protection.

U.S. officials later said the soldier had left his base camp with three Afghans when he was captured. Locals in eastern Paktika province reported that a U.S. soldier went missing in the area on Tuesday.

The Taliban-allied Haqqani network, considered to be one of the deadliest militant factions in Afghanistan, operates in the region.   

The U.S. military says it is using all of its resources to find the soldier and provide for his safe return.  

The news came as 4,000 U.S. Marines began a major anti-Taliban offensive early Thursday in southern Afghanistan.  Officials said the missing soldier was not part of that operation.  

Some information for this report was provided by AFP and AP.