U.S. tightens security in wake of Brussels attacks

(NBC News) ISIS has claimed responsibility for Tuesday morning’s deadly terrorist attacks in Brussels.

At least 31 people were killed and hundreds more wounded when suicide attackers detonated bombs in a subway car and at the Brussels Airport.

President Obama was briefed on the tragedy during his visit to Cuba, and pledged to help Belgium find those responsible and bring them to justice.

“We stand in solidarity with them in condemning these outrageous attacks against innocent people,” Mr. Obama said.

Security was increased at airports and train stations throughout the United States.