Washington CNN  — 

The Pentagon will soon issue a new policy on cluster bombs, abandoning a previous plan that mandated the military ditch older versions of the controversial weapons by 2019, according to a copy of a Defense Department memorandum signed by Deputy Secretary of Defense Patrick Shanahan and obtained by CNN.

“The Department will retain cluster munitions currently in active inventories until the capabilities they provide are replaced with enhanced and more reliable munitions,” the memorandum said.

The memo called the weapons “an effective and necessary capability.”

Cluster bombs – which not only deliver an initial explosion on impact but also contain multiple smaller bombs that spread over a wide area – are largely condemned by the international community due to the risk of civilian casualties when they’re used in populated areas.

Over 100 countries, including most members of NATO, have called for a ban on the controversial weapon and human rights groups have expressed concerns over civilian casualties resulting from cluster bombs.

The United States is one of several nations – including China, Israel, Iran, North Korea, Russia and Saudi Arabia – that have rejected a ban on the sale or use of cluster bombs.

In 2016, Human Rights Watch accused the Saudi Arabia-led coalition in Yemen of using American-made cluster bombs in civilian areas, an action that not only would have violated US export laws but also would raise further questions as to why lawmakers and military officials condone the sale and use of the weapon.

The Saudi government has denied using cluster bombs in populated areas.

In 2008 then-Secretary of Defense Robert Gates ordered the military to cease using older types of cluster bombs by Jan. 1, 2019, and to retain only newer versions of the bombs that explode at least 99% of the time or have advanced safeguards that would automatically defuse unexploded ordnance, reducing the risks of injuring civilians.

In April, Democratic Sens. Dianne Feinstein of California and Patrick Leahy of Vermont introduced a bill that would have banned funding for cluster bombs that do not meet a 1% unexploded ordnance standard.

The Defense Department memo also calls on the Pentagon to purchase only the newer, safer version of the bombs and bans exports of the older versions.

“This was a hard choice, not one the department made lightly,” Tom Crosson, a Department of Defense spokesman, told CNN.

While the new policy removes the automatic ban on the older version of the munition, Crosson said “the new policy remains committed to the same end-state of the 2008 policy: acquiring safer and more reliable weapons that ensure both effectiveness on the battlefield and minimal risk of noncombatant and friendly casualties.”

“Ultimately, it was clear to DoD’s senior leadership that removing use of current stocks would have created a critical capability gap for our forces, risking much greater military and civilian casualties in a conflict, and weakening our ability to deter potential adversaries,” Crosson added.

The new policy was first reported by Reuters.