Authorities in London are treating the major security incident near the Houses of Parliament on Wednesday as a terrorist attack.
All along, many citizens of the Western countries are clearly bracing themselves for such attacks to happen in 2017, according to a YouGov poll.
In France, which was targeted in two major terrorist attacks in the past two years, 81 percent of people thought a major incident was likely in 2017.
This chart shows the perceived likelihood of a major terrorist attack in Western Europe and USA (in percent)