“Fool me once, shame on you. Fool me twice “

We’re all familiar with that old saying. But what do they say about fool me thrice?

That’s exactly what Russia has done: violating the Intermediate-Range Nuclear Forces (INF) Treaty three times over.

In the late 1980s, the INF Treaty between the U.S. and the USSR eliminated intermediate-range ballistic missiles from the two superpowers’ arsenals. The ban applied to conventional and nuclear ground-launched ballistic missiles and cruise missiles, as well as their launchers.

The idea was to make for a more stable, secure Europe. But obligations established by treaties don’t always last forever.

Russia reportedly first violated the INF Treaty in 2008, when it tested a missile with a prohibited range. It is not clear when the U.S. learned of the violation — whether it was during the Bush or the Obama administration — but it should have surprised no one. Russia has violated almost every single arms control agreement it has signed.

But the Obama administration, at least in its early days, would have had little interest in squawking about the violation. It was busy negotiating a New Strategic Arms Reduction Treaty (START) with Moscow. Publicizing Russia’s flouting of the INF Treaty would hardly make New START ratification any easier.

The State Department never officially accused Russia of the INF Treaty violations until July 2014, about six years after the initial problematic test.

Since then, Moscow has systematically escalated its violations, moving from testing to producing to now deploying the prohibited missile into the field. The obvious goal is to intimidate our European allies and demonstrate U.S. political weakness in the face of these continuing violations.

The Obama administration’s rather measly objections to the Russian violations failed to make any tangible difference in Moscow’s calculus. Moscow simply produced its own counteraccusations, arguing that U.S. missile defense systems and armed drones violate the INF Treaty. (They don’t.)

So the question remains: What should the Trump administration do about the Russian violations?

First, the U.S. should continue to develop a comprehensive, layered ballistic missile defense system capable of protecting our homeland and our allies. Continuing to make ourselves vulnerable to Russian blackmail is foolish. U.S. leadership on missile defense will not only mitigate the Russian ballistic missile threat, but it also will contribute to political unity within the alliance.

Second, the U.S. should sanction individuals and organizations involved in the Russian intermediate-range ballistic missile program as well as those who make nuclear threats against U.S. allies. Sanctions are largely symbolic, but this step would let Moscow know that the days of no-cost treaty violations are over. The world’s leading democracy governed by the rule of law must do more than send letters opposing the violations.

Third, the U.S. should withdraw from the INF Treaty. According to Air Force Gen. Paul Selva, vice chairman of the Joint Chiefs of Staff, Russia does “not intend to return to compliance” with the INF Treaty. The U.S. is the only party that feels constrained by the treaty’s provisions.

This potentially creates a capability gap and a thinking gap within the U.S. government. Experience teaches us that the U.S. will not seriously exploit the potential of capabilities that are restricted by arms control agreements. Sticking with this broken treaty means that we will deprive ourselves of useful knowledge that might come in handy in the future.

The Trump administration should work closely with our allies to counter the inevitable Russian disinformation campaign that will try to pin the blame for the treaty’s demise on Washington. But it is Russia that rendered the treaty void, not only by refusing to come back into compliance with its provisions but also by escalating its violations.

It might be a tough sell across the pond, but good things do not come without effort. The time for the U.S. leadership in Europe is well past.