The U.S. will not be sharing data about its nuclear forces with the Kremlin after Russian President Vladimir Putin announced last month that he will suspend Moscow’s participation in the START treaty, an agreement that limits both countries’ nuclear warheads and missiles. “Since they have refused to be compliant with that particular modality of New START, we have decided to likewise not share that data,” White House National Security Council Coordinator John Kirby said in a call with reporters Tuesday. “We would prefer to be able to do that. But it requires them to be willing as well.” Signed in 2010, the treaty restricts each side’s nuclear arms to 1,550 deployed warheads and 700 deployed missiles. It represents the last nuclear arms pact between the U.S. and Russia, the world’s biggest nuclear powers.