Officials say the policy change is an effort to prevent civilian casualties.

In a major change, President Donald Trump has rescinded restrictions placed on the U.S. military’s use of anti-personnel landmines during the Obama administration.

In an effort to prevent civilian casualties, a new Defense Department policy will only allow the use of landmines with a 30-day self-destruction or self-deactivation feature.

“As part of President Donald J. Trump’s steadfast commitment to ensuring our forces are able to defend against any and all threats, the President has canceled the Obama Administration’s policy to prohibit United States military forces from employing anti-personnel landmines outside of the Korean Peninsula,” Stephanie Grisham, White House press secretary, said in a statement.

“The Department of Defense has determined that restrictions imposed on American forces by the Obama Administration’s policy could place them at a severe disadvantage during a conflict against our adversaries,” she added. “The President is unwilling to accept this risk to our troops.”

Under a new Defense Department policy, combatant commanders will be authorized “in exceptional circumstances, to employ advanced, non-persistent landmines specifically designed to reduce unintended harm to civilians and partner forces.”

The change in the Pentagon’s landmine policy was first reported by CNN on Thursday.

In 2014, President Barack Obama issued a ban on the U.S. military’s use of landmines, except for the Korean peninsula, and also directed the destruction of mines not to be used for that purpose.

That ban brought the U.S. in line with the 1997 Ottawa convention that barred the use of persistent anti-personnel landmines that didn’t self-destruct.

The use of landmines has been controversial given the number of civilians who have been maimed or killed from un-exploded anti-personnel mines from previous conflicts.

The more than seven million landmines in the U.S. military’s stockpile are non-persistent — meaning they will not explode after a certain time.

Under the new policy, the military will only be allowed to use landmines that have a 30 day or less shelf-life. These “smart” mines will have self-destruct timers that can be set for hours, days or up to 30 days.

The Pentagon says that these types of landmines have only a 6-in-1 million chance of being active after a pre-determined time.

Jim Mattis, Trump’s first defense secretary, authorized a review of the ban on landmine use that culminated with the recommendation for a change in policy.

“Landmines are one of many other important tools that our commanders need to have available to them on the battlefield, to shape the battlefield and to protect our forces,” Mark Esper, the current defense secretary, told Pentagon reporters ahead of the White House announcement of a change in policy. “At the end of the day, we want to make sure that we have all the tools in our toolkit that are legally available and effective to ensure our success and to ensure the protection of our soldiers, sailors, airmen and Marines.”

Esper said the use of the landmines would “take into account both the safety of employment and the safety to civilians and others after a conflict.”

The shift in policy was necessary because “the strategic environment has changed, according to Victorino Mercado, who is performing the duties of Assistant Secretary of Defense for Strategy, Plans and Capabilities.

With the Pentagon returning its strategic focus to China and Russia, Mercado told a small group of reporters on Friday that the restoration of deterrence will help to deal with a “strategic imbalance.”

He said the value of using land mines in a conventional fight is that it enables commanders “to shape the battlefield” and redirect opposing forces away from exposed forces.

Mercado said he did not expect to see landmines being used in current conflict zones like Afghanistan, Iraq and Syria.