The Obama administration has intensified the American covert war in Yemen, exploiting a growing power vacuum in the country to strike at militant suspects with armed drones and fighter jets, according to American officials…

The recent operations come after a nearly year-long pause in American airstrikes, which were halted amid concerns that poor intelligence had led to bungled missions and civilian deaths that were undercutting the goals of the secret campaign.

Officials in Washington said that the American and Saudi spy services had been receiving more information — from electronic eavesdropping and informants — about the possible locations of militants. But, they added, the outbreak of the wider conflict in Yemen created a new risk: that one faction might feed information to the Americans that could trigger air strikes against a rival group.