With Russia's most vocal critics imposing economic sanctions over Crimea, some of Moscow's allies are also questioning its actions in Ukraine.
In Syria's civil war, China and Russia have together blocked tougher action against President Bashar al-Assad, denouncing foreign support for the rebels as a breach of Syrian sovereignty.
Now, China has quietly split from Russia over Crimea -- on the same issue of sovereignty.
"China always respects the sovereignty and territorial integrity of all states. The Crimean crisis should be resolved politically under the frameworks of law and order. We call on all sides to remain calm and exercise restraint to avoid further escalation of the tension," said Chinese Foreign Ministry Spokesman Hong Lei.
China wants nothing that might encourage separatist tensions, making Crimea a costly move for Russia, said American University professor Keith Darden.
"China has a very strict anti-secession One-China policy. It requires international support for its positions on Taiwan. The idea that by popular referendum some part of the country could decide that it's no longer part of the country without the approval of the central government is something they are never going to sign on to. So Russia is isolating itself by this action," explained Darden.
When Russia vetoed a draft UN Security Council resolution on Crimea, China abstained, saying more should be done to de-escalate the crisis.
U.S. officials say they are consulting closely with China on Ukraine, trying to further isolate Russia by portraying its actions in Crimea as outside international norms.
"Our hope continues to be that many members of the international community, including China, are in coordination and cooperation about the illegal steps that Russia took in this case and the pressure that needs to be exerted from not just the United States, but countries around the world," said U.S. State Department Spokeswoman Jen Psaki.
Russian troops taking charge in a former Soviet republic also raises questions about whether Moscow will maintain the post-Cold War status quo.
"Kazakhstan, for example, is absolutely alarmed by the idea that Russian-speaking populations should have the right to determine whether they would secede and become part of the Russian Federation. Within the Commonwealth of Independent States, Russia has been enshrining the principle of sovereignty, and that's partly why it has had good relations with Kazakhstan and some of its neighbors. Undoing that is going to cause a lot of havoc in those relations," said Darden.
President Vladimir Putin maintains that Russia is not to blame for the crisis in Crimea. He has called an early April meeting of the post-Soviet Commonwealth of Independent States to discuss the crisis in Ukraine.