A blue-ribbon Pentagon panel has urged the Trump administration to make the U.S. arsenal more capable of “limited” atomic war.

The Defense Science Board, in an unpublished December report obtained by CQ Roll Call, urges the president to consider altering existing and planned U.S. armaments to achieve a greater number of lower-yield weapons that could provide a “tailored nuclear option for limited use.”

The recommendation is more evolutionary than revolutionary, but it foreshadows a raging debate just over the horizon.

Fully one-third of the nuclear arsenal is already considered low-yield, defense analysts say, and almost all the newest warheads are being built with less destructive options. But experts on the Pentagon panel and elsewhere say the board’s goal is to further increase the number of smaller-scale nuclear weapons — and the ways they can be delivered — in order to deter adversaries, primarily Russia, from using nuclear weapons first.

Critics of such an expansion say that even these less explosive nuclear weapons, which pack only a fraction of the punch of the bombs America dropped on Japan in 1945, can still kill scores of thousands of people and lead to lasting environmental damage. They worry that expanding the inventory of lower-yield warheads — and the means for delivering them — could make atomic war more thinkable and could trigger a cycle of response from adversaries, possibly making nuclear conflict more likely. And, they say, such an expansion would cost a lot of money without necessarily increasing security.