If the United States has responsibility, it is because the CIA used Al Qaeda operatives to take advantage of the Arab spring movement.
covert branches of the US and Saudi governemtn are doing everything to
stoke up a war with Syria that can conflagrate into a war with Iraq. In
fact, Donald Rumsfeld himself initiated rebel action against Assad
during the Iraq war. See http://www.theguardian.com/news/blog/2008/nov/10/usa-terrorism
Obama, like LBJ, has done great things for civil rights, but like LBJ, he is totally owned by the military industrial complex.