Military leaders say we're about 10 years away from autonomous weapons systems that can decide without human intervention whether to inflict harm, but a recent report suggests the Pentagon needs to use that time to get ahead of adversaries who may use the technology for evil.

Gen. Paul Selva, vice chairman of the Joint Chiefs, this week talked about the "terminator conundrum," where adversaries build autonomous weapons systems that can make lethal targeting decisions.

"I think we do need to examine the bodies of law and convention that might constrain anyone in the world from building that kind of a system. But I'm wholly conscious of the fact that even if we do that, there will be violators," he said at a Center for Strategic and International Studies event.

While he said the U.S. could get "dangerously close" to that line, it's a "very bright line" Americans are determined not to cross. Equipment may become autonomous, but the decision of whether to strike will always rest with a human, he said.

The Defense Science Board's "Autonomy" report, released this week, cautioned the Pentagon from repeating mistakes made in the past, like in cyber and electronic warfare, by focusing too much on developing American capabilities without worrying about developments made by the rest of the world.

"It should not be a surprise when adversaries employ autonomy against U.S. forces. Preparing now for this inevitable adversary use of autonomy is imperative," the report says.

The report also says that the U.S. should expect and plan for other countries to not have the same high moral standard as America, allowing autonomous platforms to make lethal decisions.

"Despite understanding that autonomy used against U.S. forces provides both a threat and an opportunity, DoD capabilities and knowledge in this area are fragmented, often compartmented, and provide little opportunity to benefit from both offensive and defensive technologies, techniques and programs," the report says. "What needs to be done is better integrate these activities."