NATO has had to wait nearly 18 months for Turkey and Hungary to finally sign off on letting Sweden join the military alliance. Despite the long wait, there is a good deal of excitement in Brussels about the 32nd member. One NATO diplomat told me that Sweden's membership was the "missing piece of the jigsaw," completing the alliance's security architecture in the Nordic, Arctic, and Baltic regions. To understand, it's enough to just look at a map. Sweden is the fifth largest country in Europe -- bigger than Germany -- stretching 1,600 kilometers…