We have very specific threats currently. Traditional focus on directed attacks from abroad may be considered less likely but smaller attacks from more 'local' threats who are inspired by ISIS in very small groups is the current concern.
The global context of the diminishing Islamic State, the push for what are termed 'foreign fighters' to stay in their host countries rather than travel, and the difficulties in movement to join ISIS, all contribute to a greater local threat.
The US events of recent times show some of the motivations of individuals. These are people who have a) pledged allegiance to ISIS b) embraced a very narrow ideological and superficial but powerful religious political narrative of 'us v them' c) speak of, as mass-murderer Omar Mateen did, a US and Russian conspiracy with the West's acquiescence, to support Assad against the Sunni Muslims and d) revenge attacks for attacks against ISIS.
These motivations, which are often held by people with criminal backgrounds and may come from disenfranchised and underprivileged communities, have created a cocktail where the political and ideological narrative can appeal.
Online technology has helped individuals securely connect, stay in contact with and share tactical information with other like-minded individuals - though for small attacks with small groups this is not significant.
These are different to the larger and mainly centrally coordinated types of attacks we were experiencing and expecting since 7/7 and 9/11 or before that.
So the threat and factors have changed and are arguably harder to police and harder to stop than what we had 20 or 15 years ago.
There is, though, in the UK at least, much better intelligence, better engagement within communities than across the rest of Europe, better programs where we can and have engaged returnees from conflict zones where terrorists operate and also some success when it comes to counter terrorism prevention policies.