After passing on dinner with the French president to take a date in the City of Light with his wife last month, President Obama took leave of his Russian hosts on Tuesday night to seclude himself in his Moscow hotel with Michelle and their daughters. The decision to brush off the Russians on one of his two nights here miffed some in the Moscow government who did not understand why he would not devote the scarce time to his hosts. Mr. Obama has seemed tired here, several times fumbling the pronunciation of Mr. Medvedev’s name and Mr. Putin’s title. Beginning...