SEOUL, South Korea>> Was it a poorly executed assassination or did North Korea want to showcase its stockpile of banned chemical weapons? The use of the highly toxic VX warfare agent to kill the estranged half brother of North Korea’s leader has raised questions about Pyongyang’s real motives in one of the strangest killings the world has seen. Some say North Korea, in allegedly bringing a U.N.-classified weapon of mass destruction to kill a man at a busy international airport, intended to show the world what it can do with chemical weapons, which are easily forgotten amid concerns about the country’s advancing nuclear missile technologies.