Why is Wali-i-Musi (the somalian pirate), taken to the US?

I am not opposed to the somali pirate being taken to the US to be tried. I am just curious about what makes it that it’s in the jurisdiction of american law.

Does international maritime law say so? Does the nationality of the ship where it’s based make it a part of that countries territory, like the case with an embassy? Will then captured pirates routinely be taken to these countries to be tried? If somalia wouldn’t have been in disarray, would he have been tried there?