You're not wrong, except that USA is/was not always literally "keeping waters open" for everyone. The Cuba blockade, which is another form of war and has dire consequences for the population, has been going on for decades: https://en.wikipedia.org/wiki/United_States_embargo_against_...

This is factually incorrect. Blockade is not a synonym of embargo. Blockade is generally an act of war, and embargo is not. Dealing with Cuba is certainly a huge PITA for the majority of trading actors because of potential blacklisting in the US, but waters around Cuba are as open as they can be, and you can check marine traffic to make sure that ships arrive to Cuban ports. Even from the US itself (cause there are exceptions from embargo such as food, and medicines).