The chairman of embattled telecom giant Huawei Technologies Co. is pushing back against claims his company conducts espionage for the Chinese government, contending that Huawei is being unfairly targeted without any proof. “If they believe there’s a backdoor, they should offer evidence to prove it,” Liang Hua told reporters on the sidelines of the World Economic Forum in Davos this week.

But the U.S. says that Huawei’s very structure, with its close ties to the Chinese government and role as a supplier of key hardware in telecommunications,...