Every president you've lived under has sent Americans to kill and die in other countries, either with or without congressional oversight. Usually without. For reference, neither Korea nor Vietnam were ever declared wars by congress. For Vietnam Congress authorized LBJ to take "all necessary measures to repel any armed attack against the forces of the United States". Korea was never a war, and instead was undertaken solely at POTUS's discretion as a "police action" in response to a UN resolution and while Congress did support the effort to procure money and blood to spend in Korea, they never formally authorized any sort of aggression in Korea.