Britain’s former secret intelligence service chief has warned that the U.S. is in danger of losing its spot as the most powerful country in the world due to a “more assertive” China.

According to The Telegraph, Sir John Scarlett said he had observed a return to “great power tension and rivalry” that was growing “month-by-month.”

“As a non-American looking at the U.S. ... I can see pretty clearly the sense of agitation and anxiety is becoming more visible and audible because for the first time you [Americans] can perhaps contemplate a situation where leadership, innovation, technology doesn’t automatically find itself in the U.S.,” he said during an Oracle technology conference in San Francisco last week.

“In fact it may be in a very dynamic nation state which operates on quite a different basis from us,” he added.

Scarlett's remarks come after earlier reports that Chinese spies have compromised U.S. companies via malicious chips in servers heading to Silicon Valley that were manufactured in China. The chips provided a backdoor way in for the attackers. The companies noted in the report, Amazon and Apple, have denied the accusation, and Apple CEO Tim Cook even called on Bloomberg to retract the story. As for China, it said that it is a “resolute defender of cybersecurity.”

China is also feeling the heat from tariffs imposed by the Trump administration on billions of dollars worth of imported Chinese goods. In fact, earlier this month it was reported that the economy in China is starting to feel the impact of slowing growth, increasing debt and a trade war with the U.S.

China’s economy grew 6.5 percent during the three months ending in September on a year-over-year basis, marking its slowest economic growth rate since the beginning part of 2009. In addition, China’s stock market has declined by more than one-quarter since January’s peak and is one of the worst-performing stocks markets around the globe this year. Its currency is close to a ten-year low compared to the U.S. dollar and companies are having a hard time borrowing from lenders, with some even defaulting on loans.