Essentially that's correct. I'd use slightly different wording, but you're dead on. The United States takes the view that the Northwest Passage is an international strait used for international navigation. That has a very particular context in international law. If your body of water is a strait used for international navigation, then there is a navigational right. This exists, for example, in important areas like the Strait of Malacca and the Strait of Gibraltar. This is a critical issue.
On February 26th, 2013. See this statement in context.