WASHINGTON (Web Desk) – The United States said on Monday that, in coming weeks, it will release how many terrorism suspects and civilian casualties the US has killed in its drone strikes since 2009, the first-ever disclosure surrounding the US’s most controversial lethal operations.

Lisa Monaco, Barack Obama’s counter-terrorism and homeland security adviser, said in a Washington speech on Monday that the expanded transparency would bolster public support for drone strikes and other counter-terrorism practices that she indicated would last “for years to come”.

The long-desired disclosure will cover strikes in undeclared US battlefields, such as Pakistan, Yemen, Libya, Somalia and elsewhere, rather than the active war theaters of Iraq, Afghanistan and Syria. There was no specific date set for release, White House officials said, though Monaco said it will occur in the “coming weeks”.

“Not only is greater transparency the right thing to do, it is the best way to maintain the legitimacy of our counter-terrorism actions and the broad support of our allies,” Monaco told the Council on Foreign Relations on Monday.

As Monaco spoke, the Pentagon confirmed it had conducted a massive airstrike in Somalia that left 150 people dead, one the largest casualty totals in a US military attack of the post-9/11 era, theguardian reported.

Monaco said the administration intends the disclosure to occur annually, though she and her colleagues have less than a year remaining in office and it is unclear if their successors will institutionalize the disclosure of what Obama aides have for years suggested was a highly classified assessment. A key congressional leader argued on Monday for codifying the disclosure in law.

Cori Crider, an attorney for drone strike victims at Reprieve, said that though this was a step in the right direction, “it doesn’t go nearly far enough”.

“In every region where we have pursued an aggressive, secret drone policy, militancy has gotten stronger. It’s not enough to tally up the drones’ body count – we need a thorough reassessment of the program itself.”

Human rights groups have for years called upon the administration to release hard data about its lethal counter-terrorism strikes and interpreted the administration’s reluctance as an indication that the strikes kill vastly more people than US officials – who rarely speak for the record – acknowledge.