Even as Turkey prepared to take delivery of Russia’s S-400 air defense system, engineers at Lockheed Martin were apparently optimistically painting Turkish flags on to what would have been Ankara’s first eight airframes.

While U.S. officials clearly say moves to eject Turkey from the multi-nation Joint Strike Fighter project are not irreversible, those deliveries now seem impossible. Sending the aircraft upon which the United States, and its European and Asian allies, are betting so heavily would be a serious mistake. Yes, Russian-operated air defense systems (in particular, in Syria) are almost certainly already attempting to probe and understand its secrets. But letting what was once America’s closest Mideast ally fly the jets repeatedly in training against the Russian system would deliver far more insight than anyone would want.

The United States and its allies—including Britain, with all its distractions—must be clear-eyed about what has happened here. Russian President Vladimir Putin’s offer to sell the system to Turkish counterpart Tayyip Erdogan was a deliberately mischievous move to undermine the NATO alliance. It is part of a wider strategy that includes fostering the far right, promoting conspiracy theories, and raising the spectre of the 20th century’s worst political nightmares. It has included a military intervention in Syria that has allowed Russia to test its weapons while inflicting catastrophic human home. And, of course, Russia’s resurrected military is going out of its way to intimidate the neighborhood in a way not seen since the Cold War.

In this case, Putin’s gambit has succeeded—and there may not be much the West can do to stop it. Turkey will lose money, influence, and access to aircraft it clearly genuinely wanted. But there needs to be a next move when it comes to Russia. Putin must be made to feel a cost—ideally without doing anything that catastrophically further escalates tensions.

Luckily, there is a relatively simple answer. The F-35s already earmarked for Turkey, I believe, should be sent somewhere else to Russia’s near-abroad, where they can worry Moscow’s planners and reassure America’s European allies. That means sending them to Eastern Europe, perhaps at a concessionary rate.

If one wanted to really, really infuriate Putin – in a possibly quite dangerous way — then of course there is always Ukraine. It’s not clear that the circumstances warrant anything so extreme. Plus, frankly, the risk of secrets falling into Russian hands from that particular move might be something America and Europe’s NATO members want to avoid.

Another option would be to send the jets to one of the Baltic states, most likely Estonia or Lithuania, to augment NATO’s Air Policing mission and potentially train local pilots. That would dramatically increase the ability of NATO’s easternmost members to defend themselves, and the training could be provided relatively readily through other NATO states. These are progressive, forward-leaning democracies that desperately need Western support;shoring them up is a perfectly reasonable response to Russia getting one over us on Turkey.

The easiest option, though, might be Poland. In May, Warsaw formally expressed interest in buying 32 F-35s to replace its own aging Soviet jets. Given his closer-than-usual relations with Poland’s right-wing government, that is a deal President Donald Trump might genuinely enjoy doing. It would also send an unambiguous message to Moscow that the cost of their dealings with Turkey is the built-up defense of NATO states Russia once dominated.

To an extent, Turkey’s actions are simply the result of decades of Mideast policy coming home to roost. Western interventions, coupled with ruthless use of arms exports to shore up autocratic states such as Saudi Arabia, have made us no safer. Still, it’s hardly a surprise to see Russia returning to Cold War tactics.

Still, there’s always another move. Moscow might believe its attempt to destabilize European and Western politics will help it in the long run, but the lessons of the twentieth century are that such activity never really helps anyone in the long run. No Western democracy should relish spending money on armaments that could help its people in other ways—but in a time of rising global tensions, they may simply have little choice but to do so.