President Donald Trump said Tuesday that the federal government would not finance California’s high-speed rail project, escalating tensions over the state’s long-delayed infrastructure plan.

Trump’s comments come as his administration undertakes a formal compliance and performance review of the project, raising doubts about the future of the rail line. Transportation Secretary Sean Duffy announced in February that the Federal Railroad Administration would conduct the probe.

“It’s hundreds of billions of dollars for this stupid project that should have never been built,” Trump said while taking questions alongside Canadian Prime Minister Mark Carney. “This government is not going to pay.”