The jist from the US State Department is: "a Canadian crew aboard a
Canadian
vessel traveling through American waters with no intent to carry funds or
commerce to the Cuban people is "at risk" of removal from their vessel and
seizure of their boat. The U.S. Coast Guard would be operating within
their
legal jurisdiction if they were to take such action...even for vessels
that
are clearly noncommercial."

Doesn't Canada have anything to say about this?