One way to resolve these prisoner dilemmas and races to the bottom is through laws that bind all players, in this case an international treaty and founding of something akin to an International Nuclear Energy Agency for AI.

It's not going to be easy, but humans have achieved greater things before.

One idea from AI 2040 is to have China and the US build their data centers on the other's territory, respectively. Together with hardware verification of a slowdown baked into the chips themselves, this could lead to enough verifiability and enforcability of the pause/slowdown/shutdown.