AP interview: Europol chief says foiling every terror attack is 'extremely difficult'

The head of the European police agency Europol, Rob Wainwright, right, answers questions during an interview in The Hague, Netherlands, Friday, Jan. 16, 2015. French and German authorities arrested at least 12 people Friday suspected of links to the Islamic State group and a Paris train station was evacuated, with Europe on alert for new potential terrorist attacks. The police raids came the morning after Belgian authorities moved swiftly to pre-empt what they called a major impending attack, killing two suspects in a firefight and arresting a third in a vast anti-terrorism sweep that stretched into the night. (AP Photo/Peter Dejong) (The Associated Press)

The head of the European police agency, Europol, Rob Wainwright, listens to questions during an interview in The Hague, Netherlands, Friday, Jan. 16, 2015. French and German authorities arrested at least 12 people Friday suspected of links to the Islamic State group and a Paris train station was evacuated, with Europe on alert for new potential terrorist attacks. The police raids came the morning after Belgian authorities moved swiftly to pre-empt what they called a major impending attack, killing two suspects in a firefight and arresting a third in a vast anti-terrorism sweep that stretched into the night. (AP Photo/Peter Dejong) (The Associated Press)

Belgian police officers examine a wall in a street in Verviers, Belgium, Friday, Jan. 16, 2015. The street was blocked after security forces took part in anti-terrorist raids in Verviers, eastern Belgium on Thursday in which two people were killed and one arrested during a shootout in an anti-terrorist operation in the eastern city of Verviers. (AP Photo/Frank Augstein) (The Associated Press)