President Donald Trump on Monday expressed hope that he and the presidents of China and Russia might jointly agree to scale back defense spending, writing on Twitter that he was “certain” that such talks would take place and saying the amount of money the U.S. spends on defense is “crazy.”

“I am certain that, at some time in the future, President Xi and I, together with President Putin of Russia, will start talking about a meaningful halt to what has become a major and uncontrollable Arms Race,” the president wrote online. “The U.S. spent 716 Billion Dollars this year. Crazy!”

Trump’s tweet comes on the heels of G-20 summit, where he met with Chinese President Xi Jinping and had an informal talk with Russian President Vladimir Putin. A formal, bilateral meeting with Putin had initially been scheduled for Trump’s G-20 trip but was canceled in the wake of Russian military aggression against Ukraine.

The U.S. president did not outline what further steps he might take toward ramping down defense spending by three of the world’s largest militaries. He has long pledged to strengthen the U.S. military but has also complained often about spending on a government-wide basis.

Trump announced last October that his administration would pull out of the landmark 1987 Intermediate-Range Nuclear Forces Treaty, which bans the deployment of intermediate-range missiles on land, claiming that Russia violated the treaty. The treaty, which offered some protection to European allies, eliminated ground-launched ballistic and cruise missiles with ranges of 300 to 3,400 miles.

In addition, New START, a separate nuclear weapons reduction treat, is set to expire in 2021. Russia has called for extending the treaty for five years, though the U.S. has yet to agree to that step.