National security adviser John Bolton is meeting with Russian President Vladimir Putin today to discuss President Trump’s decision to withdraw from the 1987 Intermediate-Range Nuclear Forces Treaty, or the INF. On Monday, President Trump confirmed the plan to withdraw and said he would build up the U.S. nuclear arsenal.

President Trump: “Until people come to their senses, Russia has not adhered to the agreement. This should have been done years ago—until people come to their senses—we have more money than anybody else by far, we’ll build it up. Until they come to their senses— when they do, then we’ll all be smart and we’ll all stop. And by the way, not only stop but we will reduce, which I would love to do. But right now, they have not adhered to the agreement. It’s a threat to whoever you want— and it includes China, and it includes Russia, and it includes anybody else that wants to play that game.”

Many experts fear a new arms race. Other countries have spoken out against Trump’s move to withdraw from the INF nuclear treaty, including France, Germany and China. Ahead of his meeting with Putin, John Bolton held talks with top Russian officials Monday, including foreign minister Sergey Lavrov. Bolton reportedly criticized Russia for meddling in the 2016 U.S. elections but said the actions didn’t have “any real effect” on the election’s outcome.