Armed British police officers stand guard after Eurostar services were suspended on the Brussels route because of the attacks in Belgium, at St Pancras international railway station in London, Tuesday, March 22, 2016. Authorities in Europe and beyond have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Matt Dunham)

Checkpoints outside of airport checkpoints necessary, security experts say

Terrorists directed by ISIS detonated bombs in Brussels that killed dozens of victims in an airport and metro system,.

A woman is evacuated in an ambulance by emergency services after a explosion in a main metro station in Brussels on Tuesday, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, killing at least 13 people and injuring many others just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Virginia Mayo)

Explosions rock Brussels airport, subway; 31 reported dead

The Islamic State group claimed responsibility for the Brussels attacks, saying in a posting on the group’s Amaq news agency that its extrem…