To understand why dumping the INF Treaty is so dangerous, it’s important to understand why the treaty was signed in the first place
The National Interest explains why intermediate-range missiles are a great way of starting an all-out nuclear war without ever intending to:
If President Donald Trump goes through with his threat to withdraw from the Intermediate-Range Nuclear Forces (INF) Treaty, he will make a serious mistake that will not only destabilize European security and undermine NATO, but could lead to dangerous consequences for strategic nuclear stability between the United States, Russia and China.
To understand why dumping the INF Treaty is so dangerous, it’s important to understand why the treaty was signed in the first place. During the Cold War, the superpowers both decided to field systems that filled the gap between the use of small battlefield nuclear weapons and the horror of a strategic nuclear exchange by creating a class of “intermediate” weapons that could conduct nuclear war in the European theater, but without reaching the U.S. and Soviet heartlands—at least not immediately.
The problem, of course, is that one man’s “intermediate-range” weapon is another man’s “strategic” weapon. Putting aside war-gaming delusions about sustainable command and control, such strikes would be hard to discriminate from strategic strikes, and catastrophic escalation would be all but certain.
Ronald Reagan and Mikhail Gorbachev solved this problem by leaving both battlefield and strategic arms in place but severing the link between them that could lead too quickly to general nuclear war. Critics of the original treaty decried this as undermining NATO’s security, but in reality nothing had changed: The Soviet Union still had conventional superiority, and NATO still had a doctrine of nuclear first-use in the event of invasion.