Just make stuff up and then pretend you are highly intelligent, that's the ticket!
If intentionally created contrails are real then there needs to be a mechanism to create it.
Mechanical means either something added to the fuel or a secondary route to disperse the chemicals.
If it is mixed in the fuel there would be no way to turn it on or off unless the chemicals activation happens due to such things like atmospheric pressure, exhaust temperatures, or intentionally rich fuel mixtures leaving unburnt fuel in the exhaust. Pilots would notice such things, numerous pilots... so many it would be impossible to keep the secret.
If contrails are from a secondary source, that means physical evidence people would notice. Mechanics, ground crews. Someone would have to fill a tank with the contrails making slop.
Just make stuff up and then pretend you are highly intelligent, that's the ticket!