An American drone strike last week killed a midlevel operative with the Islamic State who had been a conduit for the militant group’s outreach to extremists in North Africa, Defense Department officials said on Monday.

The Pentagon said that the militant, Tariq bin al-Tahar bin al-Falih al-’Awni al-Harzi, a Tunisian who had been a “person of interest” in the 2012 attack on the American diplomatic mission in Benghazi, Libya, died in coordinated airstrikes on Islamic State targets near Mosul, Iraq, on June 15.

A military official declined to say how the Pentagon had received proof that Mr. Harzi was killed, but said there was now certainty that “the airstrike struck its intended target.”

In announcing the June 15 airstrikes last week, the United States Central Command said that American warplanes had conducted seven strikes, hitting two Islamic State tactical units, one fighting position, a mortar firing position, an excavator, a rocket system, a structure and a vehicle. One military official said that Mr. Harzi was in the vehicle, and that there were no known civilian casualties.

Col. Steve Warren, a Defense Department spokesman, said on Monday that Mr. Harzi had operated closely with extremist groups throughout North Africa and the Middle East. “His death,” Colonel Warren said, “degrades ISIL’s ability to integrate North African jihadists into the Syrian and Iraqi fight and removes a jihadist with long ties to international terrorism.” ISIL is an alternative acronym for the Islamic State.

Last month, the State Department announced multimillion-dollar rewards for information leading to the whereabouts of four Islamic State leaders, including Mr. Harzi.

Mr. Harzi “played an increasingly important role for ISIL as a jack-of-all-trades,” said Seth G. Jones, a terrorism specialist at the RAND Corporation. “He recruited fighters from Europe and North Africa, helped them travel to Iraq and Syria, procured weapons and other matériel, and organized attacks. This made him an extremely dangerous enemy for the U.S. and a versatile asset for ISIL. In addition, his links with ISIL recruitment and financial networks in such locations as Europe, Africa and the Arabian Gulf helped ISIL expand from a local group to a more globalized organization.”

Mr. Harzi’s role in the Benghazi attacks remained unclear on Monday. That attack, on Sept. 11, 2012, killed J. Christopher Stevens, the American ambassador to Libya, and three other Americans.

A senior Pentagon official described Mr. Harzi as a “key planner of the Benghazi attack” and a top planner of the Islamic State’s suicide attacks, including truck bombings in places like Ramadi, Iraq.