Vladimir Putin's power grab in Ukraine isn't a singular case of revanchism by Moscow. Ambitious states like China—long unhappy with aspects of the status quo in Asia—are watching Mr. Putin and learning how to test their neighbors' resolve. Absent a firm Western response to Russia's strongman, this portends greater instability in Asia.
Mr. Putin himself has likely drawn dangerous lessons from recent history in Asia, where China has chipped away at its neighbors' claims of sovereignty over territory such as the Senkaku and Spratly islands. Most of China's neighbors are now weaker than it is, and even Japan feels pressured by China's military rise.
Moscow has also watched the Obama administration give little support to Asian allies who have asked for help. The Philippines has been left on its own to try to resist China's seizure of Scarborough Shoal in the South China Sea. Since November Washington has offered almost no response to Beijing's declaration of an intrusive air defense identification zone over the East China Sea, including the Japan-administered Senkaku Islands.
In the case of North Korea, Mr. Putin has watched Kim Jong Un strengthen his position over the past two years, even after breaking an agreement not to launch missiles or conduct nuclear tests. Any sanctions put on Pyongyang are routinely watered down and undercut by China and Russia, with effectively no reaction from the United States.
Instead of concrete action, Asia has gotten American rhetoric about a "rebalance" to the east. Aside from a few minor (though useful) moves, little has changed since the Obama administration began assuring Asia that it was the new center of U.S. foreign policy. Mr. Putin undoubtedly noticed this, too.
Now that Mr. Putin has moved into Ukraine, it should be clear to all that America's diminishing credibility abets aggressive opportunism. The sense that Washington lacks the will to oppose revisionist actions-such as knocking small countries from control over disputed territory-must be part of Beijing's calculations as it pushes ever more aggressively in the East and South China Seas. Beijing correctly guessed that Washington would acquiescence to China's new air defense zone, even if U.S. military planes insisted on continuing to fly through the area.
Another lesson from Crimea is that opportunistic moves often take status-quo powers by surprise. Just days before Russia's invasion, U.S. intelligence agencies were certain that Moscow would make no military moves. The U.S. has likewise been caught off guard by China's actions, from setting up a new administrative control mechanism for the South China Sea to risking open conflict with Japan over the Senkakus.
The scourge of territorialism is back, globally. While Russia threatens to carve up Ukraine, struggles over state control rage in Afghanistan, Syria and elsewhere in the Middle East. Asia's maritime and land-based territorial disputes no longer make the continent an outlier. And when so many states are tussling with neighbors (and with non-state actors), others wishing to revise the status quo may find the prospect of further conflict ever more attractive.
Washington could improve this difficult state of affairs by reversing defense cuts that have reduced military cooperation with partners and cut the number of ships and planes available to maintain America's presence in the Pacific and beyond. U.S. forces could also be more visible around hotspots like the Spratlys and Senkakus, both to reassure allies and to send a message about Washington's commitment to stability.
Moral outrage and rhetoric are not enough to keep peace. Steady pressure from revisionist states like China eventually forces other nations into panicked responses or surrender. Those with few resources to protect their interests can only be further threatened when great powers choose not to help protect the global order.