By announcing its intent to withdraw from a decades-old nuclear weapons treaty, the United States is targeting Russia, which it says violated the bilateral deal -- but also China, which is developing arms that are banned under it.
Beijing is not a signatory to the Intermediate-Range Nuclear Forces Treaty (INF), so it's Russia that has been singled out for violating the accord, signed in 1987 by Ronald Reagan and Mikhail Gorbachev.
At issue is Moscow's new 9M729 ground-based missile system, which Washington says has a reach that exceeds 500 kilometers (300 miles) -- a claim the Kremlin denies.
"Russia has not unfortunately honored the agreement, so we're going to terminate the agreement and we're going to pull out," US President Donald Trump said Saturday at a campaign rally in Nevada.
Trump did not say whether a new treaty could be negotiated, but he has repeatedly in recent days pointed the finger of blame at both Moscow and Beijing, saying the US would develop its own weapons until they stop.
"Until people come to their senses, we will build it up," Trump told reporters Monday at the White House, referring to the US arsenal.
"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."