As the U.S. exit from Afghanistan nears, we can expect to hear steadily more about the lessons we should have learned since international intervention in the country back in 2001. But one dimension of the Afghan effort that might get overlooked next year is this: how has the Afghan conflict impacted transatlantic solidarity?

The short answer is that transatlantic relations may well be another long-term victim of the war in Afghanistan.

The Afghan operation started as a spectacular demonstration of the solidity of the transatlantic alliance in the aftermath of September 11, 2001, when NATO activated Article V of its collective defense clause for the first time in its history. But the limits of cooperation were quickly demonstrated, eroding the foundations of transatlantic solidarity. Whether they can be fully restored remains to be seen.

Afghanistan has been a story of frustration on both sides of the Atlantic. One of the early disagreements was over the relative importance of military operations versus a broader political approach – while the United States tended to focus on the former, European states emphasized the latter. The resources that each side was capable and willing to engage in Afghanistan played a role in this initial difference, but this doesn’t explain everything. Europeans had a genuine problem with the U.S. approach, which, over the years, kept focusing on security at the expense of politics and a sustained effort at national cohesion. As a result, all Afghan political institutions were created in a way that reflected Washington’s desire for expediency rather than a need to ensure the political system’s sustainability.

Torn between their willingness to demonstrate solidarity with Washington after 9/11 and their perception that the goals of the mission, as defined by Washington, were unachievable, many European countries limited their investment to the minimum and sought instead to bring their troops home. Others, in particular the closest American allies, decided to stick to U.S. strategy even when they knew it was bound to fail. These allies paid a heavy human, financial and political price, but seemed to take some absurd comfort in the fact that the failure would be a collective responsibility.

In parallel, the temptation in Washington to blame the Europeans for the coalition failures in Afghanistan grew as it became increasingly clear that, despite the official rhetoric, the United States had achieved none of its objectives. If al Qaeda has been weakened, none of its local affiliates has been eradicated and its reemergence remains a possibility in 2014 and beyond – the reality is that the Afghan state that is emerging from the reconstruction effort is in no position to prevent this happening on its own once U.S. forces have withdrawn next year.

Ironically the impending exit from Afghanistan has only exacerbated ill feelings on both sides of the Atlantic. In spite of the principle “in together, out together,” Washington decided unilaterally to withdraw, but felt let down when some of its partners decided to anticipate its own departure.

The consequences of this mutual frustration are unlikely to be spectacular. European states are too dependent on the United States for their own security to snub Washington. Nor is Afghanistan the sole reason for Washington’s diminishing commitment to European security. With the existential threat of the Soviet Union long gone and given European governments’ dwindling capacity to contribute to collective security, the continent no longer constitutes a strategic concern for Washington. At the same time, the war-weary and fiscally-stressed United States is increasingly reluctant to commit to foreign military adventures. These two phenomena, neither of which is directly or exclusively related to Afghanistan, are pulling the two sides of the Atlantic apart.

Future conflicts may not exactly look like Afghanistan, but there is a good chance they will share some of its characteristics, in particular the primacy of politics and the relatively secondary character of military force. In Afghanistan, most U.S. allies concurred with the perception that the conflict could not be solved kinetically. However, for a variety of reasons, they never really stood against that dominant U.S. paradigm. Instead, they let themselves become part of a succession of U.S. military strategies that all proved short lived.

The result of all this is a collective failure that from next year will very likely translate into a loss of credibility not just for the U.S., but for the entire Western alliance.

This article was originally published by CNN.