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. But in a warning published Thursday in the journal Science, a group of independent scientists and lawyers objected. 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. "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 ... who contributed to the critique. "You haven't just released a transmissible virus - you've released a disease," he added. The Defense Advanced Research Projects Agency, or Darpa ... launched the Insect Allies research program in 2016, budgeting $45 million over four years to transform agricultural pests into vectors that can transfer protective genes into plants within one growing season. The critics said publishing the new research findings could establish "preliminary instruction manuals" for developing offensive biological weapons. Foreign military programs are often "driven by perception of competitors' activities," the critics warn, and "the mere announcement of this program may motivate other countries to develop their own capabilities in this arena - indeed, it may have already done so."