Commentators at Foreign Policy warn that the end of the START treaty between Russia and the United States threatens not just a renewed arms race, but the erosion of what little mutual trust remains between Moscow and Washington.

The magazine notes that once the treaty expires, there will be no legal barriers left to stop either side from expanding its nuclear arsenal. How exactly this expansion might unfold is unclear for now. At the same time, the article stresses that both the U.S. and Russia face resource constraints that will prevent them from immediately exploiting these new opportunities to the fullest.

According to Foreign Policy, the most alarming consequence of START’s collapse is not a rapid build-up of warheads in the short term. The authors fear that, further down the line, both countries may choose to modernize and restructure their forces in other ways. That, they argue, would destroy the remaining fragments of trust and make any return to meaningful arms control arrangements far more difficult.

The article also notes that if one side becomes convinced that the other is trying to lock in nuclear superiority-something Russia and China have repeatedly suspected the United States of doing-then transparency and data exchange could come to be seen as a direct threat to its ability to withstand a first nuclear strike. In such a scenario, the logical response would be to shield one’s nuclear forces as much as possible from outside observation.