BARCELONA, Spain (AP) — The U.S. government's fight to ban Chinese tech giant Huawei from next-generation internet networks appears to be flagging.

The two sides faced off Tuesday at the world's biggest mobile technology trade fair, in Barcelona, Spain, where they sought to win over customers and governments.

The U.S. argues Huawei is a security risk as it could give the Chinese government backdoor access to snoop on internet users worldwide. Huawei rejects the claim, which it says is part of the United States' broader effort to stifle China's economic and technological ascent.

On Tuesday, a t...