An anti-ballistic missile treaty no longer makes sense, when there were only two or three sides and all of them had enough missiles to overwhelm their adversary, there is no point in even trying to build an ICBM defense program.

There is a huge precedent of ICBM defense programs being canceled due to large costs and questionable benefits in the face of a full scale attack from Russia.

That is no longer the case, now North Korea has a handful of missiles, with no ballistic missile defense the US would be vulnerable to an attack from North Korea.

Sure, such an attack would result in a retaliation. But the duty of the government is not to avenge it's citizens but to protect them in the first place.

There's a classic clip of Putin breaking out in laughter when an interviewer suggests the missile shield in Eastern Europe is meant to defend against Iran: https://youtu.be/7LyfwHYB8xw