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. Last Updated: 07/27/2016

INSIDE RUSSIA: VIEW FROM AMERICA: U.S. Vision of Us and Them Under Threat

However they turn out, the events in the Balkans of the past days signify more than the latest challenge for NATO or the American doctrine of intervention. They signify something much greater. For better or worse, they close the curtain on that brief period of optimism known as the post-Cold War.

Accustomed since 1991 to saying that we were living through a period of historical limbo, we can now be fairly sure that the United States has entered a distinctly new phase in its global relations. We cannot be sure that it bodes well for us or for the rest of the world.

All three world wars of the 20th century - including the Cold War - brought political and economic benefits to the United States that were well worth the sacrifices made by its citizens during the time of conflict. American peace and prosperity were seen by a majority of leaders, both at home and abroad, as complementary to that of other nations whose citizens joined with ours in pursuit of common goals. That pattern of consensus now appears to be over for years to come.

Nobody has defined tangible goals today beyond vague, moral judgments. The world as a result is now bifurcating along a dangerous and apparently irreversible line - with or against the United States.

Important countries such as China and Russia, however harsh their rhetoric, may show restraint in their opposition to U.S. objectives. But there will come a day when restraint no longer will coincide with self-interest. Smaller states, many that we now call our allies, will quickly re-evaluate priorities depending on geopolitical proximity and exposure to regional threats. Without strategic statesmanship, the time is not too far off when the United States might face a hostile world, perhaps united against it at every corner. This outcome would be particularly ironic and sad if it resulted from frustration with and reaction to American means in spite of widespread agreement over ends.

Is a fortress America that farfetched? Fifty years ago when the plans for an Atlantic alliance were brought to fruition, the architects of NATO thought according to national patterns. The French proposed satellite arrangements much like the Paris Metro or the French colonial system. The British preferred concentric circles, as their own colonial rule or careful urban planning would suggest. It was curious then that nobody really asked about the American geopolitical image. What did it look like? The answer is so obvious that it was taken for granted: the frontier. Americans draw a line - with us on one side and our adversaries on the other.

Drawing lines or building fences can be a deadly mistake in a world without a common threat or purpose. Impressive military tactics and deft diplomacy can only postpone the inevitable consequences of conceptual inadequacy at the core.

To preserve itself as the pre-eminent world power, the United States must hone subtle necessities to induce its friends and sophisticated means to isolate its enemies. We can only hope our friends and enemies - both present and future - allow us the time to do so.

Kenneth Weisbrode is deputy director of the Program on International Security at the Atlantic Council of the United States. He contributed this comment to the Los Angeles Times.