American flag (flags.com)
Whatever the causes of what happened that day, the US has learned many valuable lessons. After the USS Liberty, the US has stopped sending small, unarmed ships into dangerous positions with no backup. On June 7th, 1967 the nearest US forces to the Liberty were over 1000 miles away. America had assumed that it was too powerful and too important to be attacked. It was inconceivable that America would be attacked, particularly from its own ally.
That thinking was fatal. It took the US Navy time to learn the lessons, and that time proved too late for the USS Pueblo, which was captured off the coast of North Korea in early 1968. Since then, the only time American ships have been truly alone, without backup, are nuclear submarines spying on Russia during the 1980s and '90s. (Those subs were fully equipped with nuclear torpedoes and easily able to slip away if trouble arose.) This proves the simple lesson that the US was taught: No matter how safe it seems, there should always be backups to any military mission. Consequently, almost all American military missions have gone into battle or deployment knowing that if something went wrong, they had reinforcements and a way to safety. Even in the most secret attacks like the Bin Laden raid, the Navy SEALs went into that compound knowing that if anything went wrong, they could count on several more helicopters carrying more Americans.
This is a lesson that can be directly traced back to the story of the USS Liberty. This is the barrier that was broken in the situation. A barrier broken is an obstacle removed, or a lesson learned. Before the Liberty, America thought it was essentially invincible. It thought nobody would dare attack it, because it was the greatest country on earth. That kind of thinking was a barrier. That barrier caused it to lose the lives of many soldiers and sailors on that day and before. With the attack on the Liberty, American leadership was finally able to break that barrier and realize its vulnerability. It was able to implement measures to prevent this from happening again. That is the legacy of the Liberty, and how it has helped America move forward.