WASHINGTON — The United States military has carried out twice as many airstrikes against Islamic State militants in Libya since President Trump took office as it has publicly acknowledged, raising questions about whether the Pentagon has sought to obscure operations in the strife-torn North African nation.

The total number of strikes — eight since January 2017 — is relatively small. But the uptick points to the threat that the Trump administration believes Libya still poses, despite the president’s focus on the American-led campaign against the Islamic State in Syria and Iraq that he has trumpeted as one of his administration’s signature national security accomplishments.

Counterterrorism specialists warn that the Islamic State and Al Qaeda also still pose formidable threats in places like Somalia, Yemen and West Africa. On Tuesday, Gen. Thomas D. Waldhauser, the head of the Africa Command, said in congressional testimony that “we are heavily involved in the counterterrorism piece” in Libya.

On its website and in news releases, the Africa Command has acknowledged only four airstrikes in Libya in the last 14 months against the Islamic State, also called ISIS, ISIL or Daesh. All of the attacks have been carried out since September.