(VOVworld) – US officials say they have information that terrorist groups, including al Qaeda and IS are planning terrorist attacks on US citizens abroad, particularly in Europe. The warning was issued by the US State Department on Thursday.

It said the attacks could be carried out by lone-wolf extremists on public transportation or in public places without warning and that terrorist attacks in Europe are likely as IS members who are European citizens return from Syria and Iraq. The US and its western allies have been conducting airstrikes against IS in Iraq and Syria since August, 2014 so they will be targets of retaliatory attacks by terrorist groups.