If you are an American taxpayer, you are entitled to “Thank you” cards from the people of the 27 other NATO countries. But don’t blame the Postal Service if they don’t arrive.

Not only does the United States heavily subsidize our European allies by paying a significantly disproportionate share of our common defense, their general view is that they are doing us a favor by letting us. Having discussed this with many Europeans, I believe that their favorite book is “Tom Sawyer.” England, France, Germany, et al., have mastered Tom’s knack of persuading his friends that he is doing them the favor by letting them paint his fence.

The United States makes up 35 percent of the population of NATO countries; we pay 75 percent of NATO’s budget. The guideline for NATO members is that military spending should be 2 percent at least of Gross Domestic Product. As Steven Erlanger noted in The New York Times on April 23, aside from the United States, “only Britain and Greece now meet that number … and Britain is slipping below it.” We spend more than 4 percent.

The disproportion between our military spending and that of our wealthy allies is greater than the percentage we spend on NATO, though, because we also pay for a global deployment of military power outside the NATO framework, while our allies spend very little.

There is no logical explanation for our heavily subsidizing the defense of Europe. But there is a historical one.

At the end of World War II, the nations of Western Europe and Central Europe were poor and weak in the aftermath of the war. While the Soviet Union had also lost a great deal of its wealth and productive capacity, it put much of what remained into its military, harshly repressing civilian demand. So the United States stepped in with our military to protect the former against the latter.

Two of these three factors no longer exist. The nations of Europe are economically strong, and the Soviet Union has disappeared, replaced by a much weaker, non-expansionist Russia. One thing remains unchanged: The U.S. still spends billions of dollars a year to protect our prosperous NATO members against a non-existent threat.

Our European allies decided as they recovered from WWII to put their wealth into enhancing their domestic quality of life, and we agreed to provide the military shield behind which they continue to do this. As Zbigniew Brzezinski says in his new book, “The Strategic Vision,” “the European powers chose to leave the more costly task of maintaining global security to America in order to use their resources to create a lifestyle of socially assured security (from the cradle throughout early retirement).”

I am not arguing here that England, Germany, France, Spain, etc. should significantly increase their military spending, especially in this difficult economic period. But, given the fact that they do not feel they are in any military danger, there is even less reason for the United States to maintain a large military presence there at a cost of billions every year.

In addition to helping us reduce our budget deficit without reducing Social Security cost-of -living increases for moderate-income older people, or cutting back on aid to college students, sharply reducing our military presence in Europe lets us cut the deficit without negative effect on our domestic economy.

There are other examples of unnecessary defense spending explained almost entirely by inertia — the failure to cut back spending that is no longer justified because the historical reasons for it have gone away.

We are still as fully prepared to launch an all-out thermonuclear assault on the Soviet Union as we were at the height of the Cold War. We have three ways to deliver these weapons: intercontinental ballistic missiles; the Strategic Air Command and nuclear submarines.

I do not advocate complete U.S. nuclear disarmament in the foreseeable future. But given the greatly diminished strength of what is now Russia, we would in no way lessen our national security if we directed the military leadership to recommend two of those three delivery systems and let us save additional billions by cutting out one.

This choice would have some domestic impact, and we should hold off implementing it for a year at least, until our economic recovery is stronger. But over the 10-year time frame we have set for reducing unnecessary expenditures to help reduce our annual deficits, giving ourselves the financial benefit of having won the Cold War makes sense from every standpoint.

Barney Frank is a retired congressman and author of landmark legislation. He divides his time between Maine and Massachusetts.