US President Donald Trump said he wants to start denuclearization talks with Russia and China, returning to an issue he has raised before, as he also seeks to revive stalled diplomacy with North Korea, Reuters reports.

“One of the things we are trying to do with Russia and China is denuclearization, and that is very important,” Trump told reporters before his meeting with South Korean President Lee Jae-myung at the White House on Monday. “I think denuclearization is a very important goal, but Russia is ready for it, and I think China will want to do it too. We cannot allow the proliferation of nuclear weapons. We must stop nuclear weapons. The power is too great.”

At an event at the White House earlier on Monday, Trump said he had raised the issue with Russian President Vladimir Putin. He did not provide specific details about when the conversation took place. 

“We are talking about limiting nuclear weapons. We will involve China in this,” Trump said. “China is far behind, but they will catch up with us in five years. We would like to denuclearize. It is too much power, and we talked about that too.”

 Earlier, the US president expressed his desire to meet with North Korean leader Kim Jong-un this year.