US Secretary of Defense Ash Carter (L), together with Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford, speaks to press during a briefing at the Pentagon in Washington D.C., the United States, on March 25, 2016.[Photo/Xinhua]

The Pentagon has announced that U.S. forces have killed a senior Islamic State leader, who was among several key members of the militant group eliminated last week.

U.S. Defense Secretary Ashton Carter explained more about the leader's identification.

"We are systematically eliminating ISIL's cabinet. Indeed, the US military killed several key ISIL terrorists this week, including we believe Haji Iman, who was an ISIL senior leader serving as a finance minister, and who also is responsible for some external affairs and plots. He was a well-known terrorist in ISIL's ranks, dating back to its earliest iteration as al-Qaida in Iraq...when he worked under Zarqawi as its liaison for operations with Pakistan."

The attack was the latest in a string of air strikes targeting the terror group's leadership.

Carter said the removal of Haji Iman would hamper the group's ability to conduct operations both inside and outside Iraq and Syria.

It's unclear if there was a link between Haji Iman and this week's deadly terror attack in Brussels.

Earlier this month, the Pentagon announced it had killed Omar al-Shishani, often described as Islamic State's "Minister of War".