US President Donald Trump has officially banned the US government from using the majority of products made by Chinese telecoms makers Huawei Technologies and ZTE.

The ban was part of the bigger Defense Authorization Act signed by the president on Monday. It will apply to US government agencies as well as their contractors.

The act covers certain telecommunications gear and services from Huawei and ZTE, as well as video surveillance equipment from major Chinese suppliers including Hikvision, Hytera and Dahua. Anything deemed “substantial”, “essential” or “critical” will be banned -- a broad definition that could apply to many products, including network services and even smartphones. 

Huawei told Abacus that the decision was “ineffective, misguided, and unconstitutional.” In a statement it added: “It does nothing to identify real security risks or improve supply chain security, and will only serve to stifle innovation while increasing internet costs for US consumers and businesses.”

ZTE declined to comment.

For ZTE, it’s the latest development in what has proven to be a complicated relationship with the White House.

In April, the US government banned American companies from selling to the Chinese telecoms maker after it failed to punish employees who breached sanctions against Iran, and for covering up its actions and then lying about them.

The ban could have been fatal for ZTE, which sources up to 30 percent of its components from US companies. Trump later reversed the decision, ostensibly arguing it would kill too many Chinese jobs, but seeing it as part of wider trade negotiations with China.

Huawei isn’t a stranger to government scrutiny either. In 2012, the company was banned from bidding on Australia’s National Broadband Network (NBN) due to cybersecurity concerns. It has since been blocked from supplying phones to Australia’s defence force.