"We are obviously concerned about unintended harm to civilians as a result of the whole range of munitions out there that are used in war," Bryan Whitman said in a news release. "It is for that reason that we have taken a leading role in the negotiations on cluster munitions, but within the framework of the (U.N.) Convention on Conventional Weapons."

The Convention on Conventional Weapons includes all nations that produce cluster munitions, China and Russia among them.

More than 90 countries were in Oslo, Norway, to sign the document that bars signatories from using, producing, selling or stockpiling cluster munitions.

Defense Secretary Robert Gates signed new standards for cluster bombs in July that aim to strike a balance between operational requirements and safety concerns, Whitman said, with the goal of reducing collateral effects of cluster munitions used to legitimate military objectives.

The new policy is designed to eliminate the number of bomblets dispersed by cluster bombs that don't explode on impact, he said. The standards require that, by 2018, 99 percent of all bomblets to explode on contact.