The US State Department said there was no evidence so far that today's terrorist attacks in France, Tunisia and Kuwait were coordinated.
State Department spokesman John Kirby said the attacks were still being investigated but there was "no indication on a tactical level they were coordinated."
"Obviously, clearly, they were all terrorist attacks," Kirby said at a news briefing.
Suspected Islamic militants on Friday killed at least 37 people at a Tunisian seaside resort and 25 worshippers at a Shi'ite Muslim mosque in Kuwait, and decapitated a man at a U.S. gas company in France.
The attacks occurred during the Islamic holy month of Ramadan.
Islamic State had urged its followers on Tuesday to step up attacks during the Ramadan fasting month against Christians, Shi'ites and Sunni Muslims fighting with a U.S.-led coalition against the ultra-hardline jihadist group.
"I don't believe investigators are at a level now that they know precisely what motivated each one of these and the degree to which Ramadan itself was a factor," Kirby said. "It's just too soon to tell right now."