A key hurdle to extending a landmark nuclear treaty between the U.S. and Russia isn¡¯t Donald Trump or Vladimir Putin. It is China.

The New START treaty, the last major arms control accord between the world¡¯s two nuclear superpowers, is set to expire in early 2021. Like another key treaty covering intermediate-range nuclear missiles, which collapsed this year after the U.S. quit that accord, Trump administration officials say the agreement may not be worth extending if China isn¡¯t brought into the fold.

A failure to renew or extend the accord would mark the effective end of decades of agreements aimed at limiting the proliferation of nuclear weapons.