The US has issued a worldwide travel alert for its citizens in response to “increased terrorist threats”.
The state department said “current information” suggested the Islamic State group, al-Qaeda, Boko Haram and others continued “to plan terrorist attacks in multiple regions”.
The alert, it said, will remain in place until 24 February 2016.
France, Russia, Mali and several other countries have seen deadly attacks in the past month.
A US state department representative said there was “currently… no reason to believe that US citizens would be specifically targeted”.
The travel alert advises US citizens to “exercise vigilance when in public places or using transportation”.
They are also advised to “be aware of immediate surroundings and avoid large crowds or crowded places”.
“Authorities believe the likelihood of terror attacks will continue as members of ISIL/Da’esh (IS) return from Syria and Iraq,” the state department said.
Similar advice, which applies everywhere bar the US itself, was issued twice in 2011 – following the death of Osama Bin Laden and on the tenth anniversary of the 11 September attacks. There was a further warning in August 2013
The most recent worldwide alert came last Christmas in response to an attack in Sydney, Australia, flagging the risk of “lone wolf” attacks, a warning repeated this time using the less colourful phrase “unaffiliated persons”.
Such broad warnings have been criticised in the past, both for being so vague as to be of little practical use and for doing the terrorists’ job for them by creating a climate of fear in which governments may introduce repressive policies.
But with millions of Americans travelling this week to celebrate Thursday’s Thanksgiving holiday, US officials insist the action is a sensible reminder of the global terrorist threat.