The latest controversy over American military assistance to Ukraine has laid bare the practical impossibility of the administration’s unannounced policy of trying to help Ukraine materially but declining to do anything that might enable Russia to claim that it was now at war with the United States or all NATO and justify Vladimir Putin’s nuclear saber rattling.

In some respects, the administration has managed to get the worst of both worlds. It has attracted the ire of the Paleoconservative Buchananite right, which seems to have infected about half of the Fox News commentariat, in pretending that the federal budget is a zero-sum game and that every cent of the $40 billion authorized for military aid to Ukraine is being torn from the hands or mouths of disadvantaged Americans.

At the same time, it has failed to satisfy the traditional majority in the United States that wishes a clear and adequately ambitious objective to justify such a commitment of resources. Only three months ago, the egregious chairman of the Joint Chiefs of Staff, General Mark Milley, advised that the Russians would occupy the Ukrainian capital, Kyiv, in a few days, and absorb the entire country of more than 40 million people back into Russia within a few weeks.

Given that the United States had assisted in training up a Ukrainian Army and ready reserves of nearly 500,000 men, and that the Ukrainians were well armed with anti-tank and low-altitude anti-aircraft missiles, and Russia only had about 150,000 trigger-pullers ready for the invasion, how the joint chiefs arrived at this harebrained prediction eludes and alarms the imagination. His latest prediction, on Memorial Day, was that the war could last for weeks or many months.

As soon as it became clear that Ukrainian resistance was extremely determined and that the Ukrainian Army substantially outnumbered the forces of the invader, it was obvious that Russia would not be able to occupy and hold a very substantial area in Ukraine indefinitely without a serious reinforcement of its expeditionary force.

Yet as long as Ukraine did not possess the ability to retaliate by inflicting any damage on Russia itself, the Russians could use all Ukraine as a shooting gallery into which it would fire missiles at civilian populated areas all around the country with impunity for as long as it wished, unless the Western Alliance provided Ukraine with weapons that would return fire on Russia itself and give Russia a serious incentive to reach a compromise peace.

At the outset, President Biden flippantly offered President Zelensky and his family safe passage out of Ukraine, on the assumption they were about to be evicted by the Russians anyway. Mr. Biden has gradually followed events and supplied Ukraine generously with defensive weapons, as have other NATO allies, but he repudiated his own secretary of state in declining to approve giving Ukraine even aged Polish Russian-built fighter planes, and appears to be balking at advancing sophisticated rocket launchers that could fire projectiles even a few miles inside Russia.

The take-away message for the world, if this policy is not amended, is that Washington huffs and puffs, as Mr. Biden did in the early days with his clowning reference to the ruble becoming “rubble” and all the hot air about sanctions, but that when Mr. Putin threatens the use of nuclear weapons, the West folds like a three-dollar suitcase. The appeasers win, and the West will support the inalienable right of Ukraine to fight to the death of its entire population without having any capability to strike Russia in a way that would motivate it to accept a reasonable compromise.   

If the Ukrainians are expected to allow the Russians to rain missiles down on their entire civil population indefinitely, the war will end in, at the least, a Russian humiliation and satellization of Ukraine, a clear strategic victory, a crushing defeat for democracy and for the West, especially after all of Mr. Biden’s fatuous early bravura (once he realized the Russians wouldn’t win in three weeks), and the triumph for Vladimir Putin of having largely reversed the decisive and bloodless Western victory in the Cold War.

The addition of Ukraine to the Russian Federation, along with Belarus and Moldova, which seem already to be in the Kremlin’s orbit, would bring back under Moscow’s control about 40 percent of the non-Russian population of the Soviet Union that seceded from the USSR in 1991. Most of the rest are the Islamic Asian republics and it is unlikely that Russia wants them integrated back into Russia.

The present conditions bear some resemblance to the Korean War: Since China was directly making war on South Korea, General Douglas MacArthur felt that it was in order to inflict some effective countermeasures directly on the People’s Republic itself, and President Truman and the joint chiefs of the time demurred. It was a much more difficult question in Korea as the United States had a large army in the field and was taking heavy casualties.

MacArthur warned against sending a conscript army to the ends of the earth to risk their lives for any goal short of victory and clearly in the vital national interest. In principle, he was correct and it was a lesson that the nation paid a terrible price for forgetting in Vietnam, though the issue in Korea was muddied by MacArthur’s unacceptable public insubordination.

It is much simpler here: All the West is asked to do is rise above Mr. Putin’s absurd and totally implausible threats to employ nuclear weapons and liberate the gallant Ukrainians from the impossible burden of fighting this criminal invasion with one hand tied behind their back (by its half-hearted allies).

The West and, in particular, the United States have a clear choice: They provide Ukraine with offensive weapons that will reciprocate to some degree the civilian casualties and destruction of the homeland that Russia is now inflicting upon Ukraine with impunity, or it will be exposed as a confederation of cowardly posturers intimidated by the Kremlin’s nuclear threats, even though if they made it clear that any use of nuclear weapons by Russia would be reciprocated, as was always understood by both sides throughout the Cold War, it is Mr. Putin who would be faced down.

Mr. Putin isn’t completely insane and would only think in such terms if he were facing an unimaginable humiliation, which no one is seeking and Ukraine could not achieve anyway. The American right should stop sniveling about being at war with Russia — some body bags came back after the horrifying fiasco in Afghanistan, but none will return from Ukraine; the U.S. isn’t risking anything by standing up to Russia, which is a truncated, economically failing, corrupt regime with a GDP smaller than Canada’s, but which is populated by one of the world’s distinguished nationalities.

The Fox News and leftist isolationists should realize the strategic disaster that the crushing of Ukraine at this stage would bring. If this is what occurs, after the extraordinary valor of the entire Ukrainian population has pushed the Russians back and gained the admiration of the world, then we will have chosen shame and betrayal as our policy and we will deserve the general strategic offensive of China, Russia, Iran, North Korea, and many defectors from the palsied Western Alliance that will ensue.