WASHINGTON— U.S. troops in Afghanistan may once again engage Taliban fighters, not just al-Qaida terrorists, under new guidelines quietly approved by President Obama, administration officials say.

The armed forces were to limit their operations in Afghanistan to counterterrorism missions against al-Qaida after this year, until Obama broadened the guidelines in recent weeks. The plan comes as the U.S. combat mission in Afghanistan draws to a close, thousands of troops return home and the military prepares for a narrower counterterrorism and training mission for the next two years.

Obama’s decision also means the U.S. can conduct air support when needed.

One U.S. official said the military could only go after the Taliban if it posed a threat to American forces or provided direct support to al-Qaida, while the latter could be targeted more indiscriminately.

“To the extent that Taliban members directly threaten the United States and coalition forces in Afghanistan or provide direct support to al-Qaida, however, we will take appropriate measures to keep Americans safe,” the official said.

The Taliban’s presence in Afghanistan far exceeds that of al-Qaida, adding significance to Obama’s authorization. The president’s decision came in response to requests from military commanders who wanted troops to be allowed to continue to battle the Taliban, the U.S. officials said.