Remarkably, however, President Obama has responded to Mr. Putin’s return to the presidency by strongly affirming his commitment to partnering with the strongman. His meant-to-be-confidential assurance to outgoing President Dmitry Medvedev on Monday, that “after my election I have more flexibility” to solve “all these issues, but particularly missile defense,” was only the latest sign that Mr. Obama has decided to bet on deal-making with Mr. Putin rather than on democratic change in Russia. …

Last month Secretary of State Hillary Rodham Clinton said Moscow’s obstruction of action by the U.N. Security Council on Syria was “just despicable.” Yet last week the Obama administration agreed to support what amounts to Russia’s plan for keeping the Assad regime in power, by dispatching a U.N. envoy to broker peace. Mr. Obama’s assurance to Mr. Medvedev, meanwhile, has raised a reasonable question: What “flexibility” will Mr. Obama be prepared to offer on missile defense, given that Mr. Putin surely will not be satisfied with anything short of scrapping the system or giving Russia a veto over its use?

Mr. Obama said Tuesday that “at a time of great challenges around the world, cooperation between the United States and Russia is absolutely critical to world peace and stability.” But that cooperation — and progress on Mr. Obama’s priority of more nuclear arms reductions — should not come at the expense of U.S. defense and security interests. Moreover, Mr. Obama would be foolish to center his policy on an autocrat whose people are clamoring for democratic change. Has nothing been learned from the Arab Spring?