The Arms Trade Treaty (ATT), which President Donald Trump announced on April 26 that the U.S. would quit, is a failure. When then-Secretary of State John Kerry signed the ATT on behalf of the U.S. on September 25, 2013, hopes were high among the treaty’s friends that it would change the world.

The president’s decision didn’t crush those hopes. Reality did.

The supposed purpose of the ATT is to end irresponsible international arms sales. But as one of the treaty’s most distinguished defenders, former Assistant Secretary of State Thomas Countryman, has admitted, its terms are “clearly ambiguous.”

In fact, it contains no definitions at all. None.

Why is the treaty so vague? The ATT’s negotiators wanted to get all the world’s nations on board. The only way to do this was to make the treaty as vague as possible. But treaties are contracts that bind the United States. Being bound to vagueness is inherently dangerous.

The ATT has no rewards for compliance. The only thing you get from going along with it is a warm feeling. It also has no enforcement mechanism. Given its defects, that’s a good thing, but relying on the fuzzies to create compliance isn’t serious.

If nations around the world want to not sell arms to dictators, all they need to do is not sell. No treaty is necessary. If nations want to control their borders to prevent illicit arms imports, the same is true.

We don’t need a treaty. We need more democratic, competent governments. Without them, no treaty can work. With them, no treaty will be necessary.

The argument that progressives offer is that if the U.S. stops making arms sales the left dislikes, this will create influential “norms.” If you truly believe that Russia will become responsible if the U.S. simply does things that progressives like, good luck to you.

But there is no basis for this belief. It’s a fantasy, and a self-disarming one at that.

The progressive focus on the U.S.’s arms sales isn’t a coincidence. Iran’s arms sales don’t much bother the treaty’s advocates. But they really hate the West’s.

If you doubt this, look at what they do. When the progressive group behind the ATT wanted to quote a foreign condemnation of the president’s decision, to whom did they turn first?

To Press TV, the mouthpiece of the Iranian regime.

The treaty’s friends have sued the British government to stop its arms sales. They leak assiduously against the French government. They vehemently oppose U.S. arms sales, and — like Trevor Thrall in these pages — support the treaty as a way to stop those sales.

But they do and say nothing about the dictators.

When Rachel Stohl, one of the treaty’s most vehement defenders, wrote about the missiles that shot down flight MH-17 in 2015, who did she blame for supplying them? Vladimir Putin?

No. She blamed “today’s globalized environment.”

The treaty’s friends always condemn the U.S. in the clearest terms. But when it comes to the dictators, out rolls the poisonous fog of the passive voice in which no one is responsible for anything.

The treaty’s friends have a blame-America-first policy. They openly use the ATT as a weapon against the West, and only against it. In practice, therefore, they are siding with Iran’s mullahs, Putin and Beijing.

Worse, the ATT is part of a wider network of progressive treaties, including one on cluster munitions. That treaty, according to Jim Shields, head of the U.S. Army’s Program Executive Office Ammunition, has created “capability gaps that we are really concerned about.”

It is easy to say that the ATT will never affect U.S. arms transfer policy. The history of the cluster munitions treaty says otherwise. So do the lawsuits of the ATT’s advocates themselves.

The ATT is a treaty. A treaty is legal instrument. But arms sales are decisions of policy, not law.

The decision to authorize an arms sale should often be tough because the world isn’t black and white. It’s mostly grey. Trying to impose a legal framework on that reality is going to produce bad policy. There are lots of tough calls in foreign policy. Being against the Arms Trade Treaty isn’t one of them.