MOSCOW — It’s June 2014. War is underway in eastern Ukraine, and Russia has recently annexed Crimea. Western countries are introducing sanctions against Russian companies and the people in President Vladimir V. Putin’s inner circle. It seems that Russia will soon be completely isolated from the rest of the world.

But the 21st World Petroleum Congress is taking place in Moscow. The atmosphere at the Crocus Expo International Exhibition Center, where the congress is being held, is decidedly nonconfrontational. On a stage, two men in suits hold an amicable conversation, addressing each other as “my friend.” The men are captains of the global petroleum industry: Rex W. Tillerson, the chief executive of Exxon Mobil, and Igor I. Sechin, the head of Rosneft, Russia’s state oil company, and one of Mr. Putin’s longtime allies.

Russians rejoiced earlier this month when President-elect Donald J. Trump announced that he would nominate Mr. Tillerson as his secretary of state. If he is confirmed, it will not just be the Kremlin that benefits, but Mr. Tillerson’s “friend” Mr. Sechin in particular.

The agency Mr. Tillerson has been nominated to lead is known in Russia as “GosDep.” The word, which translates to something like “StateDep,” entered the Russian language long ago, an abbreviation in the Soviet tradition of shortening long titles for government departments. But it’s more than just a clever nickname: GosDep is a term from Russia’s internal politics, one that evokes the Kremlin’s eternal enemy.