Prime Minister Theresa May of Britain on Wednesday abruptly fired her defense secretary, Gavin Williamson, blaming him for a leak of government information about a Chinese company’s role in sensitive telecommunications infrastructure, one of the most serious such leaks in recent years.
Mrs. May’s announcement was made after an investigation into a report in the Daily Telegraph about discussions in Britain’s National Security Council, of which Mr. Williamson was a member.
The report suggested that Mrs. May had overruled objections from some senior council members to allow the Chinese company, Huawei, to build some elements of the next-generation cellular data network known as 5G, though the government later said that no decision had yet been made.
The leak provoked a negative reaction from the United States, which has been on a campaign to pressure other countries to bar Huawei from building 5G networks.
Robert L. Strayer, the deputy assistant secretary for cyber and international communications and information policy at the State Department, said any use of the Chinese company posed a potential security risk.
Suffering bitter divisions over Britain’s departure from the European Union, known as Brexit, Mrs. May’s cabinet has been notoriously ill-disciplined of late. But even by its own leaky standards, the disclosure involving Huawei broke new ground and outraged senior officials.
Mr. Williamson, once a close ally of Mrs. May, was replaced by Penny Mordaunt, the international development secretary, who become the first woman to take the top job at Britain’s defense ministry.
But the sacking marks another low point for Mrs. May and her rocky government, which has lost more than 30 ministers since she came to power in 2016.
Mrs. May’s office released a letter she had written to Mr. Williamson, in what amounted to an extraordinary public shaming of a high-ranking politician.