Of course it is. LOL.
These are treaties by any definition used by the Founders and by our constitution. So are bilateral fair trade agreements, which is what I favor over the two to ten thousand page behemoths we call "free" trade agreements.
Treaties require not just a simple Senate majority; they need a 75% vote.
Now look at the votes for NAFTA, CAFTA, etc.
What's wrong with this picture?
This is what we get by allowing our government to play word games. They are called "agreements" for a reason and that's to bypass constitutional due process. Oh, but even suggest we're going to change these "agreements" and the other parties start screaming about "broken treaties."
Congress has the plenary authority to regulate trade with foreign nations, according to the Constitution. It therefore has the authority to approve trade agreements in any fashion it so chooses.