The Taliban have claimed that they killed a US sailor and kidnapped another as Nato forces ramped up a massive search for the servicemen who disappeared two days earlier in an area held by the militants.
The coalition force set up checkpoints and distributed fliers with the sailors' pictures and are offering thousands of dollars in rewards for their return. There were conflicting reports about whether the body of one of the two had been recovered.
US and Nato officials confirmed that two American navy personnel went missing Friday in the eastern province of Logar, after an armoured sport utility vehicle was seen driving into a Taliban-held area. Nato officials were unable to say what they were doing in such a dangerous part of eastern Afghanistan.
Taliban spokesman Zabiullah Mujahid also said the pair drove into an area under insurgent control, prompting a brief gunfight in which one American was killed and the other was captured. He said both were taken to a "safe area" and "are in the hands of the Taliban".
The sailors' heavily reinforced white Land Cruiser has been recovered, according to a security official.
Another local official, Abdul Wali, the deputy head of the provincial governing council, said the Taliban sent a message through intermediaries offering to hand over the body of one sailor in exchange for jailed insurgents.
The Taliban posted a message in English and Arabic on their website that claimed one American service member had been kidnapped in Logar and said another was killed in a shoot out, according to SITE Intelligence Group. The website message included a picture of one of the fliers, showing the photo of one of the sailors, but did not say whether he was alive or dead.
Hundreds of fliers, with reprinted photos of the two missing sailors, have been distributed throughout Logar province where Nato troops were stopping vehicles, searching them and those inside. The fliers say a $20,000 reward (£13,000) is being offered for information leading to the sailors' location.
"Our latest, accurate information reports are that they are still in the area," said Din Mohammed Darwesh, spokesman for the provincial governor of Logar.
He said the governor's office was upset because the two Americans left their base without notifying Afghan security forces in Logar, which is the normal protocol. "This was an abnormal situation," Mr Darwesh said.