You may have a case - but it could be an expensive battle. NATO to only "some" people stands for the North Atlantic Treaty Organization. You have sold watch straps using what you consider to be a generic definition of the goods - "NATO" straps - that is, watch straps based on NATO (originally British) military specifications. You are correct that the Ohio company has secured several US Federal Trademark Registrations which include the acronym NATO. Thus, if you use NATO in any manner that is likely to cause confusion - you can be sued for trademark infringement.
Answered on Feb 25th, 2013 at 8:26 PM