Within the Defense Department, one agency’s recent project sounds futuristic: millions of insects carrying viruses descend upon crops and then genetically modify them to withstand droughts, floods and foreign attacks, ensuring a permanently secure food supply.

But in a warning published Thursday in the journal Science, a group of independent scientists and lawyers objected to the research, which has not yet moved out of the lab. They argue that the endeavor is not so different from designing biological weapons — banned under international law since 1975 — that could swarm and destroy acres of crops.

The dispute is the latest episode in an ongoing international debate over the pursuit of what is called dual-use research: technological discoveries that can be beneficial or pose threats to human welfare. As gene-editing tools become increasingly accessible, scientists, ethicists and policymakers are weighing the good pivotal discoveries could do for humanity against their nefarious potential.

“Once you engineer a virus that spreads by insect, it is hard to imagine how you would ever control it,” said Guy Reeves, a researcher at the Max Planck Institute for Evolutionary Biology in Germany, who contributed to the critique.