Italy was on security alert on Saturday in the wake of Spain's double terror attacks that left at least 14 people dead, including three Italian nationals.
Embassies, airports, churches and tourist destinations are among the possible targets and were under police and Army surveillance in Italy after the Islamic State claimed responsibility for the attacks in the Spanish cities of Barcelona and Cambrils, which also injured about 126 people of 34 different nationalities, Xinhua news agency reported.
Thirteen people were killed on Thursday in the popular Las Ramblas area of Barcelona when a white van zigzagged at high speed down the busy avenue thronged with tourists, knocking down pedestrians.
On Friday morning, the 14th victim, a woman, was stabbed when five terrorists jumped out of a car and began attacking people at random on the seaside promenade in Cambrils, a town south of Barcelona.
Spanish police gunned down all five attackers. The woman died in a hospital later on Friday. Six others were also injured in the attack.
As Italian officials held strategy meetings and leaders issued messages of condolences to Spain and to the victims' families, experts analysed the attacks.
Author and journalist Zouhir Louassini, a visiting professor from Granada University in Spain, said: "Spain and the Catalonia region are a hot zone, as shown by an increase in the arrests of terrorist cells there in the past three to four years."
Louassini added that the IS has reached a "level of madness" in its rhetoric, proving it is in trouble following its defeat on the ground in its Iraqi stronghold of Mosul.
"They have reached a point where they are urging people to do anything at all, to kill by any means, even a knife," Louassini said, even as news emerged on Friday of two deadly knife attacks in the Finnish city of Turku and the other in the German city of Wuppertal.
The third knife stabbing took place in the Russian city of Surgut on Saturday.
Italy's Air Force General Leonardo Tricarico (retd), who is now the president of the Intelligence Culture and Strategic Analysis (ICSA) Foundation, said that Europe will remain at risk as long as its leaders don't cooperate to fight fundamentalist terrorism together.
Since 2011, at least 30,000 foreign fighters reached Iraq and Syria from over 100 countries, of which one-fifth came from Western Europe, the Institute for International Political Studies (ISPI) said in an August 4 report.