U.S. officials worry that the death of Saudi King Abdullah ushers in a period of new uncertainty in a key relationship that already was tense.

In the short term, the death of the king actually might ease strains in the relationship. The Saudi kingdom, as it enters a period of transition, may feel more vulnerable to external threats and eager to show the world that it still has the solid of backing of the U.S.—the country the kingdom always has seen as its ultimate protector.

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