What is the Lemurian Star really doing in Captain America: The Winter Soldier?

On my 5th watching of Captain America: The Winter Soldier recently, I suddenly realised that I don't actually understand what sets the events of the film in motion.

At the start of the film, Steve Rogers, Natasha Romanoff and the STRIKE team are sent to rescue a ship, the Lemurian Star, from pirates. It turns out that;

So my question is;