President Joe Biden expressed concern that China’s economic and demographic problems have turned the world’s second-largest economy into a “ticking time bomb” that threatens the rest of the world.

Biden said at a political fundraiser Thursday that “China is in trouble” because growth has slowed and the number of people in retirement age outnumber those of working age.

“It has the highest unemployment rate going,” Biden told donors in Park City, Utah. “So they got some problems. That’s not good because when bad folks have problems, they do bad things.”

The comments are some of the most alarming yet that Biden has made about the US’s chief geopolitical rival. The president has sought to walk a fine line between deterring China’s malign economic practices and aggression in the South China Sea, while achieving a diplomatic rapprochement with Chinese leaders and put a floor under relations.

Biden said Washington is not looking for a fight with Beijing but is closely watching their activities. For example, he dubbed China’s “belt and road” infrastructure finance initiative “debt and noose” because of the terms countries must accept in exchange for the money.

The Biden administration this week released a long-awaited order curbing US investments in China, but the policy was pared back from initial drafts amid the president’s efforts to improve ties with the Chinese government.