I know that most people don’t care about foreign policy, but this is kind of important. Yesterday it became clear that America hasn’t abandoned its allies so much as switched sides.

The Trump administration is trying to bully Canada, Denmark, and the NATO countries. It just held a summit with Russia even though we once provided a security assurance to Ukraine.

It is not the case that America is retreating into splendid isolationism. No, we are still taking sides in world affairs. But now we are holding hands with the Russians and the Chinese and opposing the countries to which we have long-standing treaty obligations.

I don’t want to talk about the morality of this evolution today. Instead I want to talk about two things: the medium-term effects and whether or not this change is reversible.

You’re not going to like either answer.

Why was Russia able to invade Ukraine? Simple: Because in 1994, Ukraine gave up its nuclear weapons.

The nukes on Ukrainian soil after the fall of the Soviet Union were always controlled from Moscow, not Kyiv. But if the Ukrainians had wanted to play hard ball, they could have kept at least some of them and repurposed them into their own nuclear deterrent. If North Korea can do it, Ukraine definitely could have done it. Instead, the Ukrainians gave up all the nukes in exchange for wishy-washy security assurances from the United States, the United Kingdom, and Russia.

Well, we know how that turned out. Without a nuclear deterrent, no nation is truly sovereign. It exists at the pleasure of its nearest nuclear-armed neighbor.

This is a basic fact of life. But for 80 years America forestalled nuclear proliferation by constructing an umbrella under which allied nations could take shelter. The deal was: We would build a giant nuclear arsenal and then allied countries could credibly claim that we would act as their nuclear deterrent if they were aggressed upon.

Why did America do this? Because we are a nice country who wants everyone to get along with puppy dogs and rainbows?

No.