Not exactly, Richard.

Iran may have been acting upon what they (and the Iraqis) believed to be the boundary - or at least one that has been respected by both countries. Its called local knowlege. The Brits appeared on the scene and they made their own map and decided where they thought they boundary was without international consensus. I doubt if the Brits bothered to consult with Iran regarding the boundary, either.

For Blair to state, in the boldest of terms, that he was absolutely right was more than political posturing, it was a bold face lie.

Iran could have detained the sailors and let them go with a warning but Blair (instead of negotiating their return) created an international incident out of it which put Iran in an uncompromising position. In other words, if Blair was going to make a big deal out of it by running to the U.N., the E.U. and the U.S., Iran may have decided to keep the sailors until the question of the boundary was settled once and for all.