Why was Soleimani Assassinated?

President Trump and Mike Pompeo told us that Iranian Gen. Soleimani had to be assassinated when he was in Baghdad at the end of last week because he was on a mission to plan and implement attacks on US military and diplomatic personnel in the region. But their story is not holding up very well, as reports surface that he was on a peace mission and other US claims are not adding up. So...why was he killed?