Russia’s Vladimir Putin is ruthless when dealing with adversaries — as when his navy shot up a Ukrainian vessel seeking to enter the nearly enclosed Sea of Azov.

The facts appear to back Kiev, though no one should have any illusions about Ukraine’s governance. Moscow has become Washington’s chief bête noire. Yet America is vastly more powerful. Moreover, the Russian Federation is not the Soviet Union reborn. The former is neither a global nor an ideological competitor.

Rather, much like a pre-1914 great power, Moscow demands respect for its borders and interests. It certainly does not want to wage a war with America, which it would lose.

Europe also is able to defend itself, possessing 10 times the gross domestic product and three times the population. The fact that Europeans do not spend more — Germany devotes a bit more than 1 percent of GDP to its military — demonstrates that the continent really doesn’t fear Moscow.

However, stuck in a bad neighborhood, Ukraine wants on to America’s defense dole. But Washington already is overburdened, protecting prosperous and populous Asian, European and Middle Eastern allies.

Kiev isn’t important for U.S. security: Ukraine was part of both the Russian Empire and the Soviet Union, without much effect on America. Ukraine matters no more today.

That sounds cold-hearted, but alliances and wars should be about security, not charity.

Russia is determined to prevent Ukraine from joining militarily with Moscow’s adversaries.

Nothing at stake in the Russia-Ukraine conflict warrants the U.S. confronting a nuclear-armed power.

Washington’s chief responsibility is to protect the American people, which means remembering John Quincy Adams’ famous admonition: The United States should be “the well-wisher to the freedom and independence of all. She is the champion and the vindicator only of her own.”