If US approaches Russia, it basically sold out Ukrain and its European allies to Russia and declares its complete failure in Crimea policy. Lost of Europe is the cost US cannot afford.

If US approaches China, it has to reverse its policy in Asia Pacific, including its promised protection in East China Sea and South China Sea. That will put itself in diplomatic jeopady. It definately will alleniate its Asian allies. Even worse, It has loosen up the control over Japan, as part of the policy shift. Now it is unable to reign it back.

My sense is that US has unwillingly, or unknownly, changed its long term diplomatic principle: trade short term interests for long term strategic benifits. This could be ther results of multiple factors. Nevertheless, this is not a good news for US and the world, including China and Russia. It could potentially become a lose for everyone.

What China needs to do now are:

1. Speed up the technological development, strengthen its economy and defense, and advances its political reform cautiously but steadfastly.

2. Establish / grow / strength its allies in Asian Pacific, Central West, Midddle East and Africa. Expands its influence in all continents. Destabilize US allies, try the proxy conflict/movement to distract US focus, thin out the US resource, and stretch US fiscal burden. The goal is to rasie the cost of actual conflict, reduce the US's ability for global involvement, and postpone the inevitable clash.

3. Display China's determination and capacity in the defense of national interests. Assert the force if necessary. Meanwhile, promote China in the western style via media, diplomacy and public domain. Encourage and support all the friendly allies in all the countries.