The Islamic State is claiming responsibility for the giant explosion which killed more than 140 in Baghdad and injured as many as 200 more.
As Iraqi and U.S. coalition forces regain territory once held by the group, observers note, the Islamic State is returning to it's previous strategy of guerilla violence.
Major General Chip Chapman worked on counter-terrorism issues for the U.K.'s ministry of defence.
IN: "Two manifestations...
OUT: ...two-thousand and ten."
DUR: 13
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