President Theodore Roosevelt famously stated that, "If given the choice between righteousness and peace, I choose righteousness." The United States faces this same choice now in the Ukraine - Peace, such as allowing Russia portions of Eastern and Southern Ukraine while the Ukraine becomes a NATO member, or righteousness, such as helping the Ukrainian government to retain all of its current territory, and create independent areas in the East and South as previously existed in Crimea. While the troubles in the Ukraine are front page news, the complex forces that drive the United States to have to choose between these two ideals are less well-known.
Of the 32 current ongoing armed conflicts around the world, only one has two states battling against each other in an interstate war. More common are "internationalized civil wars" that blend together elements of civil and interstate conflict along with non-state actors, interstate and regional organizations and regional and global powers. Internationalized civil wars are hard to influence and difficult to stop. They have limited peacemaking and military options, and as a consequence, can result in long and costly disputes.
The conflict in the Ukraine represents a complex combination of civil and interstate conflict dynamics: an intrastate conflict (and the unseating of the prior president), which led to an interstate conflict (Russia's seizure of the Crimea), which has been followed mostly recently by a second intrastate dispute with by Russian supported separatists who now hold and can clearly defend territory - in short an internationalized civil war and a political and military mess.
The United States and its partners have few, if any, good options for military responses to the Ukrainian conflict. The Ukrainian military is large, but not highly capable. The insurgents have demonstrated the ability to fight and hold territory. And critically, the Russian military, which used to be exceptionally large, out-of-date, and inept, radically reformed after its weak showing in its incursion into Georgia into a force that is (at least partially) surprisingly lean, modern and efficient. The Russian military has demonstrated effectiveness in projecting force - both in terms of military power (the rapid and well-organized seizure of Crimea) and in terms of subtle psychological operations and manipulations of social media (which have both ignited well-orchestrated protests across the Ukraine and increased global perceptions of the legitimacy of their actions). Assessing Ukrainian, Russian and insurgent capabilities reveals a military balance that is not advantageous to the sitting Ukrainian government. Nor is the situation well-suited to its allies; Ukraine's size and location make extending ground support hard, and the loss of Crimea and proximity of the Russian fleet offset American global naval superiority. Before United States or NATO allies could deploy sufficient forces to the Ukraine to defend against additional seizures or advances by the insurgent troops, Russian troops would be able to takeover and defend much of the country. Bottom line: at this time there are few good military options.
Peacemaking options in the Ukraine, such as UN mediation leading to a peace agreement, also represent a challenge. Civil wars are harder to end than interstate conflicts because they involve non-state actors (insurgents) who lack institutional mechanisms for enforcing peace agreements and states that don't want to sit down and negotiate with insurgents because they fear it lends them legitimacy. Internationalized civil wars like the Ukraine are even more difficult to peacefully resolve, as they require domestic, regional and international actors to agree upon a peace agreement through a process that can implode with the objection of any one of these many actors. And the Ukrainian case has some special difficulties, beyond these common problems, that make peacemaking especially demanding. Each of the main external protagonists (the United States/West and Russia) interprets the others' actions and intentions in a highly threatening way. The United States and its partners worry that Putin is out to restore the Russian/Soviet Empire, while Putin thinks that the West wants to deny that Russia has any legitimate security interests beyond its borders, even on its immediate periphery (a posture that the West did not take toward the Soviet Union during the Cold War). Conflict management can lead to peace even in the most horrific of circumstances (as eventually occurred in the protracted and costly dispute in the former Yugoslavia), but the road to peace in the Ukraine will likely be long, bumpy and deadly.
A return in Ukraine to the pre-seizure status quo is not going to happen, but that doesn't mean there should be no American response. The United States and its allies must however choose between irreconcilable strategic ideals: peace and righteousness - a quick, operationally defensible peace that saves lives but imposes an admittedly unjust division of the Ukraine, or a long and likely violent conflict that may retain Ukraine's sovereign independence, but with the possibilities of high human costs. Neither outcome is ideal. Worse, however, is the possibility that the American desire for a nonexistent, optimal outcome that avoids this tradeoff will lead to delays and muddled policy that result in neither peace nor righteousness. Before the Obama administration acts, it needs to figure out what it wants - peace, or Roosevelt's preference, righteousness. Efforts to find ideal actions that achieve both objectives are likely to contribute to outcomes that are bad for the Ukraine, the Ukrainian people and American interests.