Fifty years ago on April 30, Saigon fell to the North Vietnamese, and the defeat was America’s, too.

South Vietnam was our ally, whose forces we trained, armed and supported with our own troops, ultimately at the cost of more than 58,000 of our service members’ lives.

The grim anniversary is a reminder that those we support to the utmost can lose, as President Donald Trump works to prevent Kyiv from suffering a fate like Saigon’s.

Vladimir Putin’s army occupies less than a fifth of Ukraine’s territory, yet three years after he began his full-scale invasion, Putin shows no willingness to end the war, despite the price his soldiers pay in their own blood every day.

Volodymyr Zelenskyy may well believe that an American-negotiated peace promises as little safety for his country as America’s negotiations with North Vietnam promised for Saigon.

He certainly knows that’s a possibility, and the Ukrainian leader has so far been unwilling to risk any concession that might lead to complete defeat:

If Zelenskyy concedes Crimea, why wouldn’t Putin press for the Donbas as well — and more of Ukraine next time, when he’s rested and ready to send his war machine rolling again?

If peace doesn’t include a military security guarantee, either a path to NATO membership or something else that would set a power greater than Russia’s in the way of any further aggression, what will prevent it from turning out like the Paris Peace Accords that were supposed to have ended the Vietnam War in 1973, but in truth ended South Vietnam’s chances for survival?

Trump and his administration, meanwhile, take a dim view of Kyiv’s prospects if there isn’t an agreement soon — what America has given Ukraine has kept the country in the fight, but our arms and aid haven’t turned the tide of the war.

While Americans mourn the fall of Saigon, few wish we had stayed in the Vietnam War longer or believe doing so would have produced a different outcome.

Ukraine doesn’t have the benefit of American troops fighting alongside its own, as South Vietnam did — if Kyiv is expected to win, it can only draw upon our dollars and our weapons.

Impressive as those funds and material means may be, they aren’t enough to ensure victory.

This is why Trump is determined to try something beyond what’s already been tried, and for now that means putting intense pressure on Zelenskyy and Putin to negotiate.

As large as Vietnam looms in the American experience, there is a precedent closer to home for Kyiv and Moscow alike for how a war like this might end.

In 2008, Russia invaded another neighbor, the nation of Georgia, and set up puppet regimes — Abkhazia and South Ossetia — in Georgian territory.

Georgia, like Ukraine, lost control over about 20% of its land, and Russia maintains military bases in the occupied regions to this day.

Also like Ukraine, Georgia aspired to join NATO, as well as the European Union, and the Georgians have not given up that goal, though Russia’s violence has kept it at bay.

Just as Zelenskyy has refused to legitimize Russian possession of Crimea, Georgia does not recognize the Russian-occupied territories as anything other than Georgian.