The recent crisis over North Korea's nuclear weapons has had at least one unexpected aspect: the crucial -- and highly effective -- intervention of Beijing. China's steady diplomacy is a sign of how much things have changed in the country, which has long avoided most international affairs. Recently, China has begun to embrace regional and global institutions it once shunned and take on the responsibilities that come with great-power status. Just what the results of Beijing's new sophistication will be remains to be seen; but Asia, and the world, will never be the same.