US Republicans lashed out at Secretary of State John Kerry on Wednesday after he suggested that Islamist militants had a "rationale" for the attack on the Charlie Hebdo satirical magazine in Paris in January that killed 12 people.Speaking to US Embassy staff in France after attacks last Friday that killed 129 people, Kerry sought to contrast the two incidents, saying the Charlie Hebdo killings appeared to have a motivation, while those last week were indiscriminate.The magazine had angered some Muslims by publishing cartoons depicting the Prophet Mohammad and Islamic themes. The gunmen who attacked the magazine's offices were shown on video shouting: "We have avenged the Prophet Mohammad."Referring to Friday's attacks, Kerry said: "There's something different about what happened from Charlie Hebdo, and I think everybody would feel that.""There was a sort of particularized focus and perhaps even a legitimacy in terms of - not a legitimacy, but a rationale that you could attach yourself to somehow and say, 'OK, they're really angry because of this and that'," Kerry said."This Friday was absolutely indiscriminate. It wasn't to aggrieve one particular sense of wrong. It was to terrorize people," he added.