In 2014, when Russian President Vladimir Putin responded to a U.S.-backed coup that ousted a pro-Russian regime in Kyiv by occupying Crimea, President Barack Obama did nothing.
When Putin aided secessionists in the Donbass in seizing Luhansk and Donetsk, once again, Obama did nothing.
Why did we not come to the military assistance of Ukraine?
Because Ukraine is not a member of NATO. We had no obligation to come to its aid. And to have intervened militarily on the side of Ukraine would have risked a war with Russia we had no desire to fight.
Last year, when Putin marshaled 100,000 Russian troops on the borders of Ukraine, President Joe Biden declared that any U.S. response to a Russian invasion would be restricted to severe sanctions.
The U.S. would take no military action in support of Ukraine.
Why not? Because, again, Ukraine is not a member of NATO.
Clearly, by its inaction, America is revealing its refusal to risk its own security in a war with Russia over a Ukraine whose sovereignty and territorial integrity are not vital U.S. interests sufficient to justify war with the largest country on earth with its huge arsenal of nuclear weapons.
This is the real world.
And as Ukraine is not a NATO ally, and we are not going to invite it to become a NATO ally, Biden should declare so publicly, urbi et orbi, to remove Putin's pretext for any invasion.
Biden has already declared that we will not put offensive weapons in Ukraine. If, by declaring that we have no intention of expanding NATO further east by admitting Ukraine or Georgia, we can provide Putin with an off-ramp from this crisis that he created, why not do it?
Speaking last week, Russian Foreign Minister Sergey Lavrov said, "They must understand that the key to everything is the guarantee that NATO will not expand eastward."
If what Lavrov said is true — that the "key" for Moscow, the crucial demand, is that the eastward expansion of NATO halt, and Ukraine and Georgia never join the U.S.-led alliance created to contain Moscow — we ought to accede to the demand.
If this causes Putin to keep his army out of Ukraine, admitting the truth will have avoided an unnecessary war. If Putin invades anyway, the world will know whom to hold accountable.
The purposes of the Biden declaration would be simple: to tell the truth about what we will and will not do. To remove Putin's pretext for war. To give Putin an off-ramp from any contemplated invasion, if he is looking for one.
A Russian invasion of Ukraine and the war that would inevitably follow would be a disaster for Ukraine and Russia, but also for Europe and the United States. It would ignite a second Cold War, the winner of which would be China, to whom Russia would be forced to turn economically and strategically.
Thus, to avert a war, Biden should declare what is the truth:
"Ukraine is not a member of NATO, and neither we nor our allies have any intention or plans to bring Ukraine into NATO or to give Kyiv an Article 5 war guarantee."
The same holds for Georgia in the Caucasus. We did not come to Tbilisi's defense when it invaded South Ossetia in 2008 and was driven out by Putin. And we are not going to give Georgia any Article 5 war guarantee. Frankly, the time has come to declare that NATO will expand no further east and that NATO enlargement is at an end.
No more former republics of the Russian Federation — not Ukraine, Georgia, Moldova, Belarus or Kazakhstan — will be admitted to a NATO alliance whose roster is restricted to present membership.
Indeed, if the purpose of NATO is the defense of Europe from a revanchist Russia, why would we extend NATO so far to the east that it provokes Russia into attacking its neighbors in Europe?
With Russia having issued virtual ultimata, our objective has to be to prevent a catastrophe war that an invasion of Ukraine would ignite.
Such an invasion of Ukraine, a country of more than 40 million, would inevitably end with Kyiv's defeat. And the longer Ukraine resisted and the fiercer it fought, the greater the number of dead and wounded on both sides and the more enduring the hatred and hostility that would be created between them.
Already, Americans in official circles are reportedly discussing aid to Ukrainians in fighting a guerrilla war against Russian occupation troops.
There is another issue here, and that is the morality of not doing all we can to avoid an invasion and its consequent war.
Would it be moral for the United States to provide arms for a bloody insurgency if there were no realistic chance of quickly expelling the Russian invaders?
Given his problems in Belarus and Kazakhstan, Putin cannot be anticipating happily the military occupation of millions of Ukrainians.
Ending NATO enlargement could be a victory for all of us.
(Patrick J. Buchanan is the author of "Nixon's White House Wars: The Battles That Made and Broke a President and Divided America Forever.")