BRUSSELS — After the recent death of the treaty covering intermediate-range missiles, a new arms race appears to be taking shape, drawing in more players, more money and more weapons at a time of increased global instability and anxiety about nuclear proliferation.

The arms control architecture of the Cold War, involving tens of thousands of nuclear weapons, was laboriously designed over years of hard-fought negotiations between two superpowers — the United States and the Soviet Union. The elaborate treaties helped keep the world from nuclear annihilation.

Today, those treaties are being abandoned by the United States and Russia just as new strategic competitors not covered by the Cold War accords — like China, North Korea and Iran — are asserting themselves as regional powers and challenging American hegemony.

The dismantling of “arms control,” a Cold War mantra, is now heightening the risks of a new era when nuclear powers like India and Pakistan are clashing over Kashmir, and when nuclear Israel feels threatened by Iran, North Korea is testing new missiles, and other countries like Saudi Arabia are thought to have access to nuclear weapons or to be capable of building them.