As the ability of systems to act autonomously increases, those who study the dangers of such weapons, including the United Nations’ Group of Governmental Experts, fear that military planners may be tempted to eliminate human controls altogether. A treaty has been proposed to prohibit these self-directed lethal weapons, but it’s gotten limited support.

The proposed ban competes with the growing acceptance of this technology, with at least 30 countries having automated air and missile defense systems that can identify approaching threats and attack them on their own, unless a human supervisor stops the response.

The Times of Israel has reported that an Israeli armed robotic vehicle called the Guardi um has been used on the Gaza border . The United States Navy has tested and retired an aircraft that could autonomously take off and land on an aircraft carrier and refuel in midair.

Britain, France, Russia, China and Israel are also said to be developing experimental autonomous stealth combat drones to operate in an enemy’s heavily defended airspace.

The speed with which the technology is advancing raises fears of an autonomous weapons arms race with China and Russia, making it more urgent that nations work together to establish controls so humans never completely surrender life and death choices in combat to machines.

The senior Pentagon officials who spoke to The Times say critics are unduly alarmed and insist the military will act responsibly.

“Free-will robots is not where any of us are thinking about this right now,” one official told me.

What they are exploring is using artificial intelligence to enable weapons to attack more quickly and accurately, provide more information about chaotic battlefields and give early warning of attacks. Rather than increase the risk of civilian casualties, such advances c ould reduce such deaths by overcoming human error, officials say.