Probably. The US government has plenty of times in the past.
Exposing soldiers to mustard gas
The US government tested the effects of mustard gas on soldiers in the 40's without their consent.
Guatemala syphilis experiments
After WW2 the government, with the help of big pharma, infected people in Guatemala, including children, with syphilis to see how it developed over a person's lifetime and spread within a population.
During the Manhattan project some workers weren't told of the radiation risks so that the effects of various levels of radiation could be studied. Later, some people (including mentally handicapped children and adults) were even unknowingly injected with radioactive materials.
Basically similar to the Guatemala experiment except this was on US citizens.
The main ingredient in Agent Orange was tested on uninformed prisoners in Holmesburg Prison in Pennsylvania.
Military Poison Tests
From 1949 to 1969, the Department of Defense repeatedly doused whole cities across America with chemicals, bacteria, and fungal spores that they were pretty sure would be "mostly harmless." (They weren't harmless.)
MK Ultra was a project to determine if mind control could be used. The CIA used numerous methods to manipulate people's mental states and alter brain functions, including the surreptitious administration of drugs (especially LSD) and other chemicals, hypnosis, sensory deprivation, isolation, verbal and sexual abuse, and other forms of torture. Some people consented to the experimentation, but most were experimented on without their consent (including Canadian citizens.)
And those are just the ones that we know about.