Huawei Technologies, the world’s second-largest vendor of telecommunications equipment, has hired a former U.S. defense contractor official as its chief security officer as it tries to counter perceptions that the China-based firm is trying to insert its technology into U.S. systems on behalf of Chinese intelligence services.

Donald “Andy” Purdy, the former chief cybersecurity strategist for Falls Church-based CSC, began his new job Tuesday. The move comes as Congress is conducting an investigation into alleged links between Huawei and the Chinese government.

Purdy declined to comment Tuesday, but William Plummer, VP of external affairs for Huawei USA, said: “As a global information and communications technology company, Huawei takes security issues seriously. We look forward to benefitting from Andy’s expertise in cyber-related matters.”

In recent years, Huawei, whose founder and chief executive is a former technician with the People’s Liberation Army, has mounted an aggressive effort to change its image. It has hired lobbyists, consultants and a public relations firm in Washington.

In recent months, Huawei has been seeking a person with deep government connections in the United States, Britain and the rest of the world because it was worried about dwindling sales in those countries and national policies and legislation that might be hostile to its business, said an industry official, speaking on condition of anonymity.

Purdy’s move to Huawei has prompted comment in cyber and national security circles.

A former Department of Homeland Security official, Purdy has raised concerns in the past about Huawei’s efforts to enter the U.S. market, observers noted. He will certainly be able to help Huawei understand the U.S. government perspective, they said.

Huawei’s move is smart, said James A. Lewis, a cyber and China expert at the Center for Strategic and International Studies. “Huawei’s trying to show that it can be a credible partner and that we can trust them,” he said. “Andy’s widely known in the community and has a lot of experience.”

The absence of strategic trust between the United States and China in the cyber arena is notable. In 2009, the National Security Agency warned AT&T, which does lucrative business with the U.S. government, against buying equipment from Huawei.

“It’s not that Huawei would spy itself,” Lewis said. “It’s that Huawei could assist their government. It’s not that the fears are founded. It’s that we can’t dismiss them. Given the Chinese government’s record on espionage, a good-faith assertion is not enough.”