The Economist argues that realpolitik – the basing of diplomacy on power considerations – is back:

• Last month Barack Obama rolled out the red carpet for the leader of Vietnam – helping to normalize relations between the two former combatants.
• Yet another former enemy – Cambodia – was harangued about human rights abuses in a “tense” meeting.
• Cambodia has been stumbling towards democracy with (admittedly imperfect) elections recently being held.
• Vietnam on the other hand refuses to hold elections and doesn’t tolerate political dissent.
• Why the difference in treatment then? Because Cambodia is a close ally of China – a power that could potentially rival the United States in the future.
• Vietnam stands up to China. And so the United States is trying to improve relations with the enemy of its enemy.

Read more over here.

Source: The Economist