NATO members should be looking for ways to add troops and military and police trainers in Afghanistan. The withdrawal will be a blow to the Afghan province of Oruzgan, where most of the Dutch troops have been stationed since 2006 and have earned a reputation as good fighters, sensitive to local needs and concerns.

It is possible, though unlikely, that the next Dutch government could change its mind after elections this June. For now, Washington, other NATO partners and the Dutch need to reflect on how this happened and how to contain the damage.

The Dutch cabinet fell when the Labor Party, one of the main coalition partners, refused NATO’s — and Washington’s — request to extend the Oruzgan mission for an additional year. The mission had already been extended twice before. But with Dutch casualties rising sharply and the overall effort struggling, public support evaporated and the Labor Party refused to go along.

That forced new elections, in which the main issue is likely to be not Afghanistan but the more emotional question of restricting Muslim immigration to the Netherlands. The biggest parliamentary gains are expected to go to the hate-spewing xenophobic Freedom Party, which also advocates withdrawing from Afghanistan.

Centrist parties, like Labor and Prime Minister Jan Peter Balkenende’s Christian Democrats, worry about voters defecting to Freedom. But Mr. Balkenende strongly favors keeping Dutch troops in Oruzgan to reinforce NATO and to give Mr. Obama’s strategy a chance to work. Labor chose not to get caught on the unpopular side of the issue. That seems woefully shortsighted.

We fear the Dutch decision could provide cover for wavering politicians elsewhere — Germany, for example, or Canada, which is now scheduled to pull out its troops at the end of 2011.

Europe’s leaders need to tell themselves — and their voters — the truth. The war in Afghanistan is not just about America’s security. It, too, is about denying sanctuaries to Al Qaeda, which has also carried out deadly terrorist attacks in Europe. NATO is stronger when it stands together. The Netherlands weakens itself and all of its allies by choosing to stand alone.