Three candidates in Tuesday's Democratic presidential primary debate in Charleston, S.C., said they would not allow Chinese companies to build critical infrastructure in the U.S.

Former Vice President Joe Biden Joe BidenMomentum growing among Republicans for Supreme Court vote before Election Day Trump expects to nominate woman to replace Ginsburg next week Video of Lindsey Graham arguing against nominating a Supreme Court justice in an election year goes viral MORE, former New York Mayor Mike Bloomberg and Sen. Elizabeth Warren Elizabeth WarrenBiden's fiscal program: What is the likely market impact? Warren, Schumer introduce plan for next president to cancel ,000 in student debt The Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon MORE (Mass.) all said yes when they were asked by the CBS News moderators if they would bar Chinese companies from building critical infrastructure, although the discussion moved quickly into releasing tax returns.

Sixteen infrastructure sectors are classified as critical by the Cybersecurity and Infrastructure Security Agency Act of 2018, including energy, financial services and communications.

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Although the Democratic White House hopefuls didn't highlight a specific sector, Congress and the White House have been actively debating how to deal with Chinese telecommunications giant Huawei.

The company, which is the world's largest producer of telecom equipment, is heavily involved in the worldwide move to fifth generation (5G) wireless technologies.

It also provides software and hardware to many companies in rural America at comparatively low prices.

The administration and Congress have deemed Huawei a national security threat because of its ties to the Chinese Communist Party.

The Department of Commerce placed Huawei on its “entity list” in May 2019, preventing U.S. firms from conducting business with the company unless they obtain a specific license.

However, Huawei’s full inclusion on this list has been delayed multiple times to avoid disruptions to U.S. tech firms that have deals with it.

The Trump administration has also made it a priority to convince allied countries to exclude Huawei from the buildout of 5G networks.

Multiple members of Congress have introduced bills to restrict Huawei from working with American companies in communications and energy sectors.