In addition, Mr. Biden has approved a Pentagon request for standing authority to target about a dozen suspected leaders of Al Shabab, the Somali terrorist group that is affiliated with Al Qaeda, three of the officials said. Since Mr. Biden took office, airstrikes have largely been limited to those meant to defend partner forces facing an immediate threat.

Together, the decisions by Mr. Biden, described by the officials on the condition of anonymity, will revive an open-ended American counterterrorism operation that has amounted to a slow-burn war through three administrations. The move stands in contrast to his decision last year to pull American forces from Afghanistan, saying that "it is time to end the forever war."