"There's the question about whether it could be used on people who aren't fighting for a sovereign state," Moreno says.
There's also nothing in the convention about what countries can use on their own people—so countries may be allowed to use oxytocin on domestic criminals and suspects.
Moreno and other ethicists have warned that if countries don't figure out what to do with oxytocin and other neurological agents, they'll regret it. In October 2002, the Russian government used a chemical that knocked out more than 700 hostages being held captive by Chechen rebels—killing at least 130 of them in the process. According to a 2009 opinion piece in the journal Nature, "an acrimonious argument over the control of nonlethal weapons is now under way among the states that have signed the Chemical Weapons Convention … life scientists should actively discuss the effectiveness and safety of potential incapacitating agents."
Paul Zak, perhaps the country's preeminent oxytocin scientist, is currently working on an undisclosed project with the Department of Defense. It's not the first time the Department of Defense has been interested in his work.
"I went to a DoD conference and gave a spiel on oxytocin, talking about why we trust some people and why we avoid other people," he says. "Afterwards, this guy comes up to me and says 'I interrogate terrorists for a living, I need this stuff tomorrow.'"
But if the Department of Defense is looking for a truth serum, there are better alternatives according to Zak. "Valium, sodium pentothal, ecstasy … if you're going to drug people, why not drug the hell out of them," he says. By comparison, "oxytocin's effects are pretty subtle."
Zak thinks oxytocin's bonding effects—the way it might help regulate soldiers' moods and build trust within a unit—is of much more interest to the military.
"It helps you build rapport," he says. "I think just understanding how the [trust] system is tuned up or tuned down would be much more useful to the DoD and their understanding of daily life [in the force]."
But Young says it could be a dual-threat hormone.
"It builds camaraderie and ingroup cohesion, so sure [the military] would be interested in it," he says. "But, based on what scientists are doing, they've got to be thinking that maybe they can use this as an interrogation technique."
Jason Koebler is a science and technology reporter for U.S. News & World Report. You can follow him on Twitter or reach him at email@example.com