While it’s far too soon to tell whether Israel’s military strikes will cripple or even substantially set back Iran’s nuclear program, the necessity of stopping Iran’s march to a bomb is far more clear today than it was even three years ago.

Two things have happened since President Trump’s first term that alter the strategic calculus: Russia invaded Ukraine, and Hamas massacred Israeli civilians.

The first event taught the world a lesson it shouldn’t forget. When a nuclear-armed nation engages in armed aggression, the rest of the world’s options narrow considerably. If Russia didn’t possess a nuclear deterrent, it’s highly likely that Western support would have been more immediate, more intense and more decisive.

Instead, Western powers were often slow to approve new weapons transfers, and when they did provide more capable weapons, they initially placed sharp limits on their use. Western aid certainly kept Ukraine alive, but restrictions on that aid have inhibited its defense.

One could easily imagine a NATO-enforced no-fly zone, or granting Ukraine weapons and a freedom of action to use those weapons that is more similar to the freedom Israel currently enjoys. But at every step Western powers have worried that they might be pushing Russia too far. This means that aid has often been too slow and too limited to give Ukraine a viable chance of reversing Russian gains.

Russia’s nuclear arsenal, in other words, serves as the world’s most dangerous insurance policy. It grants Russia the ability to launch aggressive military operations while also exercising at least some degree of control over the armed response.