The United States has pushed Johnson to reverse his January decision to grant Huawei a limited role in 5G, while London has been dismayed by a crackdown in Hong Kong and by the perception that China did not tell the whole truth over coronavirus.
Britain's National Security Council (NSC), chaired by Johnson, will meet on Tuesday to discuss Huawei. Media Secretary Oliver Dowden will announce a decision to the House of Commons later in the day. The opposition Labour Party said his statement would be after 1130 GMT. The government has not provided a time.
The immediate excuse for the about turn in policy is the impact of new U.S. sanctions on chip technology, which London says affects Huawei's ability to remain a reliable supplier.
It is unclear how far Johnson will go on Tuesday. Telecoms firms already had to cap Huawei's role in 5G at 35% by 2023. Reducing it to zero over an additional two to fours years is now being discussed, although operators have warned that going too fast could delay key technology and disrupt services.
Asked about Huawei in June, Johnson said he would protect critical infrastructure from "hostile state vendors". Justice Secretary Robert Buckland said on Monday the "priority" would be national security.
The United States says Huawei, the world's biggest producer of telecoms equipment, is an agent of the Chinese Communist State and cannot be trusted.
Huawei denies it spies for China and has said the United States wants to frustrate its growth because no U.S. company could offer the same technology at a competitive price.
NEW COLD WAR?
In what some have compared to the Cold War antagonism with the Soviet Union, the United States is worried that 5G dominance is a milestone towards Chinese technological supremacy that could define the geopolitics of the 21st century.
Angering China just as Britain extracts itself from the European Union will put London firmly back on the side of its closest ally, the United States.
It would also mark the end of what former Prime Minister David Cameron cast as a "golden era" in ties with China.
China's ambassador to Britain has said a U-turn on Huawei would damage Britain's image and it would have to "bear the consequences" if it treated China as a hostile country.
In January, Johnson defied Trump by allowing so-called high-risk companies' involvement in 5G - including Huawei - to be capped at 35%. He excluded such companies from the sensitive 5G "core", where data is processed, as well as critical networks and locations such as nuclear and military sites.
Britain's major telecoms networks have said they need at least five years, and ideally seven, to remove Huawei.
"If we get to a situation where things need to go very, very fast, then you are into a situation where potentially service for 24 million BT Group mobile customers is put into question - outages," BT CEO Philip Jansen told BBC radio on Monday.
Huawei has said the implications of the U.S. sanctions are not yet clear, and it has urged Britain to wait. The Telegraph newspaper said on Friday the government was expected to set a deadline of 2025 for removing Huawei equipment.
(Reporting by Guy Faulconbridge and Paul Sandle, editing by David Milliken and Mark Potter)
By Paul Sandle and Guy Faulconbridge