Joe Cirincione spells out why leaving the INF Treaty is a grave mistake:

But Bolton does not want to fix the treaty; he wants to kill it. “Violations give America the opportunity to discard obsolete, Cold War-era limits on its own arsenal and to upgrade its military capabilities to match its global responsibilities,” Bolton wrote in 2014. America will pay a high price for this rigid ideology. President Trump walking out of Reagan’s treaty is a gift to Russian President Vladimir Putin. It doesn’t fix the problem; it makes it worse. Now, there will be no restraints whatsoever on Putin’s ability to deploy hundreds of missiles, should he desire. The United States will likely be blamed for the collapse of the treaty, widening the split within the North Atlantic Treaty Organization.

One of the more common defenses of Trump’s bad decision to give up on this treaty is that there is no point in staying in a treaty if the other party isn’t fully adhering to it. That defense fails to take into account that the treaty still constrains and limits what the other party can do as long as the treaty remains in force. It also fails to consider which side the treaty constrains more. Russia can and will produce and deploy a lot more of the missiles currently prohibited by the INF Treaty once the treaty is dead than it can as long as the treaty survives. Whatever problem the treaty-violating Russian cruise missiles create, that problem is sure to be much worse when there is no longer a treaty to violate.

As long as the U.S. remains a party to the treaty, it can continue pressuring Russia to return to full compliance, and it can use Russian refusal as leverage against Russia in other negotiations. Once the U.S. leaves, Russia will be free to do as it likes and they will also be able to fault the U.S. for the treaty’s demise. Instead of trying to preserve hard-won arms control architecture, the administration is deliberately demolishing the entire edifice after one part of it has started to erode.

As Cirincione says, “[W]hen someone breaks the law, the answer is not to repeal the law.” The trouble is that Bolton hates the rules contained in arms control agreements and Trump couldn’t care less about them, and so we are rushing headlong into a new arms race for no discernible reason except to satisfy Bolton’s ideological agenda.