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The US decision to shelve plans to build a missile defence system in Poland and the Czech Republic gives significant substance to the Obama administration's pledge, made soon after taking office, to "reset" strained relations with Russia. But the move is likely to increase unease among eastern Europeans about the level of Washington's commitment to their collective security and will be greeted with alarm in Israel.

The plan for the missile system, involving the stationing of 10 two-stage interceptor rockets in Poland and a linked radar station in the Czech Republic, was by far the biggest irritant in a relationship between Moscow and Washington that has deteriorated in recent years. Taking the plan off the table, at least for now "“ US officials are indicating that it...