The remaining hot spots from the Arab Spring are in Libya and Syria. In both cases, popular uprisings erupted against tyrannical governments inspired at least partially by the Arab Spring events that began in Tunisia and moved quickly to Egypt and elsewhere. Distinguishing characteristics of these two cases, however, have been the continuing brutality of the regime against its dissidents and the dogged organized resistance to the regime’s actions by those seeking change. This level of resistance and the need for continued bloody suppression distinguishes Libya and Syria from places like Bahrain and Yemen, where dissidence was fairly quickly suppressed and things returned fairly quickly to whatever passes for normalcy.

Libya and Syria are different from one another and from the others. Their duration sets them aside from other Arab Spring events. Libya has produced a full-scale revolutionary movement that, with the considerable assistance of NATO air forces, may be closing in on the overthrow of the Gaddafi regime; the effort in Syria has been less organized and militarized, but worldwide publicity has resulted in a steady drum beat of international demands for the resignation of Syrian president Bashir al-Assad that are increasingly difficult for him to resist.

The level of violence, even savagery, of government oppression of resisters in both countries has raised both to the level of international humanitarian disasters or crises–situations where there is widespread atrocity against or abuse of a country’s citizens by its government. One response to such a situation is humanitarian activism, which I define as intervention (including military force as its most dramatic manifestation) in humanitarian crises by other countries to end the conditions defining the disaster. The United States has a long, if uneven, record of action or inaction in such situations; in both Libya and Syria, however, the United States has adopted a fairly passive form of opposition to the disasters, preferring to defer leadership to others. Why?

It seems to me that to understand when the United States does and does not become personally invested in these kinds of situations requires looking at three variables. The first is American mood at the time. Is the United States feeling especially optimistic about its internal situation and place in the world, in which case it is likely to become internally activist, seeking to spread its own message and gospel to others? Or is the United States feeling insecure and recessive, turning inward and evincing a sense of isolation from world events that is part of the U.S. historical DNA?

Second is the nature of the international environment in which any proposed action might occur. Partly, this assessment reflects Americans’ self-assessment and confidence in themselves, their ability to shape the world, and their confidence in their world role. At the same time, this assessment includes the competing demands on American national security resources elsewhere in the world: can the United States afford to divert scarce resources (especially military) to humanitarian missions that can or might be needed elsewhere?

The third variable is geopolitics, and it also has at least two facets. One is the American relationship with the country in which the disaster is occurring. There were, for instance, no shortage of what now are called humanitarian crises in countries with which the United States was allied during the Cold War (Central Africa and Central America offer fine examples) where the United States did not condemn the harsh treatment of populations by “friendly” rulers; given the dangers of Cold War escalation, however, all we did with similar events in the communist world (e.g. Cambodia) was condemn them. Context may be everything. At the same time, the attitude and willingness of friends and allies is also a geopolitical factor: the United States almost certainly would not have dispatched and kept force in the Balkans in the 1990s and beyond were it not for the insistence of NATO allies.

Different periods of recent history can be gauged in these terms. During the Cold War, there was basically no such thing as humanitarian activism, because geopolitical, Cold War considerations precluded it. The term entered the lexicon after the Cold War ended, and there was a spate of such activism by the United States in the 1990s, when all the variables aligned favorably: the American mood was confident and expansive, the rest of the environment was fairly placid and undemanding, and there were few geopolitical inhibitions to preclude identifying and stomping on the bad guys who abused and denied the rights of their citizens.

And then there is now. The United States has not acted decisively in either the Libyan and Syrian cases. In Libya, we play a very limited supporting role (that has had opposition anyway), and beyond leading the verbal condemnation of Assad, have done very little in Syria. Admittedly, these are two countries where the U.S. has few interests and even fewer levers of influence it can apply, but it has clearly not been an instance of any kind of humanitarian activism by any measure.

The three variables help explain this. Two of them are negative. In the current economic climate, the United States is not feeling good and positive about itself, and were the Obama administration to propose any more than what it is doing, it would be accused of taking its “eye off the ball” of our real priorities, of trying to divert attention away from its internal problems, or both (most likely both). At the same time, the United States is still heavily invested in military adventures elsewhere in the region that strain resources; the American people would hardly embrace a new Middle Eastern military adventure. The only positive variable is international support for activism. Europe, after all, is devoting resources to Libya (which it arguably cannot afford), and even other Middle Eastern countries have condemned the Syrians. In a sense, this willingness of others to take the lead relieves the United States of any pressure it might otherwise feel to get out front on either crisis.

Libya and Syria may or may not represent the long-term future of American humanitarian activism, but they are likely to be models for the next few years, until American prosperity and self-confidence reappears and we are looking at the world differently than we are today. If one is against such interventions anyway, then “let the bad times roll,” since they are keeping us from doing what we have no business doing anyway, as Ron Paul would argue. If the United States is the shining city on the hill (Reagan’s typification) and should be ready and willing to help transform the world, wait for a better day.

Donald M. Snow, Professor Emeritus at the University of Alabama, is the author of over 40 books on foreign policy, international relations, and national security topics. This essay first appeared at his blog  What After Iraq?.