U.K. Prime Minister Rishi Sunak said the so-called “golden era” of relations with China was over, warning that Beijing’s move toward even greater authoritarianism posed a systemic challenge to Britain’s values and interests.

“Let’s be clear, the so-called ‘golden era’ is over,” Sunak said Monday in his first major foreign policy speech.

His reference to the “golden era” for the U.K.-China relationship echoed comments made by former U.K. Finance Minister George Osborne in 2015, who had claimed Britain could be China’s “best partner in the West.”

Sunak said it had been “naïve” to believe that closer economic ties over the previous decade could lead to social and political reform and accused Beijing of “conspicuously competing for global influence using all of the levers of state power.”

He warned, however, that Britain could not rely on “simplistic Cold War rhetoric.”

China’s embassy in London was not immediately available to respond to a request for comment.

Sunak has faced pressure from Conservative backbenchers to toughen his stance on China since he took over as party leader and prime minister last month.

“We recognize China poses a systemic challenge to our values and interests — a challenge that grows more acute as it moves towards even greater authoritarianism,” Sunak said in his speech at the Lord Mayor’s Banquet in London.

His comments come shortly after public demonstrations were held across China to protest the country’s stringent zero-Covid policy. A BBC journalist on Sunday was beaten and briefly detained by police while covering an anti-government protest in Shanghai.

“Instead of listening to their people’s protests, the Chinese government has chosen to crack down further, including by assaulting a BBC journalist,” Sunak said.

“The media and our parliamentarians must be able to highlight these issues without sanction, including calling out abuses in Xinjiang and the curtailment of freedom in Hong Kong.”

Sunak said the pace of geopolitical change was intensifying and “short-termism or wishful thinking will not suffice” in the face of challenges posed by Russia and China.