According to American leaders, Russia’s control of South Ossetia and Abkhazia represents an assault by an arrogant adversary on a freedom-loving ally. The John McCain campaign advocates slapping economic sanctions on Russia and pressing forward with admitting Georgia to NATO — even at the risk of confrontation with Russia. The Barack Obama campaign is less strident, but shares the assumption that the United States bears responsibility for backing Georgia in the face of Russian aggression.

This reasoning is faulty and perilous. It is based on four fallacies.

The first is that Georgia is a democracy. It is not. Elections in Georgia are riddled with fraud, and the president, Mikheil Saakashvili, has a penchant for aggrandizing his personal power at the expense of fair procedures. Abuse of citizens by predatory police is rampant in Georgia, and the judiciary is hapless and corrupt.

The second fallacy is that the people of South Ossetia and Abkhazia embrace Georgian rule. Ever since the Soviet Union began unraveling in the late 1980s, Georgia has treated its ethnic minorities poorly. That is why the people of South Ossetia and Abkhazia rose against the Georgian government in the early 1990s and why they still welcome the Russians today. Some of Russia’s other post-communist neighbors have become genuine democracies and treated their minorities fairly. Lithuania, Bulgaria and Mongolia are examples. Georgia is not part of that group.

The third fallacy is that Russia is dispensable. In fact, it is vital to helping the United States meet its three biggest strategic challenges. The first is the rise of China. Like the United States, Russia has a powerful interest in checking Chinese expansionism. The second is reducing dependence on Middle Eastern oil. Russia is the world’s largest exporter of hydrocarbons. While mild anti-American propaganda abounds in Russia, Russian schools do not portray the West as wicked root and branch. Russians treasure their cultural autonomy, but they would rather join the West than destroy it. If America is to reduce its dependence on those who truly wish it ill, Russia can help. The third challenge is fighting terrorism. Here American and Russian interests are virtually identical. Close cooperation with Russia, whose global espionage operations are second only to America’s, is crucial to success in counterterrorism.

The fourth fallacy is that Russia can be manipulated. It cannot. A decade of robust economic growth has enabled Russia to clear its foreign debts, rebuild its state apparatus, and slash poverty. The regime is not democratic, but the government enjoys broad and stable popular support.

Given Russia’s revived capabilities, it unsurprising that the Bush administration’s ill-advised push to admit Georgia to NATO provoked resistance. A pro-democratic government in Moscow would have opposed the move as strongly as the Putin-Medvedev administration has. Russians of every political stripe regard the prospect of Georgia’s admission to NATO as a menace.

America often faces a painful trade-off between principles and interests. The Russo-Georgian conflict poses no such quandary. America’s commitment to the principle of self-determination favors Russian rather than Georgian sway in Abkhazia and South Ossetia since that is what most inhabitants of these regions prefer. America’s strategic interests are served by bolstering ties with a leading oil producer, bulwark against Chinese ambitions, and essential link in the war on terror. Yet both Republicans and Democrats now back massive support for rebuilding Georgia’s military, which was devastated in Georgia’s reckless play for South Ossetia in August.

Building up a diminutive, poorly governed client state on Russia’s border is a fool’s gambit. It contradicts American principles and vital national interests.

M. Steven Fish is a professor of political science at the University of California-Berkeley and the author of “Democracy Derailed in Russia: The Failure of Open Politics” (Cambridge, 2005). He wrote this article for the Mercury News.