Italian anti-terrorism police on Wednesday arrested an Italian citizen of Moroccan origin who they said was an Islamic State sympathiser planning a truck attack.
Sweden on Monday observed a minute of silence for the victims of last week's truck attack by an Uzbek man whom police believe is a jihadist sympathiser.
Swedish police said on Sunday that they have conducted raids in the greater Stockholm area as part of an investigation into a truck attack that killed four people earlier this week.
A truck drove into a crowd on a shopping street and crashed into a department store in central Stockholm on Friday, killing three people and wounding eight in what the prime minister said appeared to be a terrorist attack.
German police were searching on Sunday for possible contacts of an IS fighter believed to be behind a terror plot against a major shopping mall.
Suspected Berlin truck attacker Anis Amri travelled by bus from the Netherlands to France before heading to Italy where police shot him dead, sources close to the investigation said on Wednesday.
Islamic State claimed responsibility for the truck attack on the French city of Nice on Saturday as French police arrested three people there in connection with the carnage that claimed the lives of at least 84 people.
French President Francois Hollande said Friday that "many foreigners and young children" were among those killed or injured after the truck attack on a crowd celebrating Bastille Day in Nice, with around 50 fighting for their lives.