A gunman killed three people and wounded five during a mid-morning tram ride Monday in the Dutch city of Utrecht. Mayor: "We assume a terror motive."
Amsterdam: The U.S. State Department offered to help investigators who are treating the stabbings of two American tourists as a possible extremist attack.
Turkey announced a series of political sanctions against the Netherlands on Monday over its refusal to allow two Turkish ministers to campaign there.
Intelligence experts estimate that the Islamic State extremist group has between 60 and 80 operatives planted in Europe to carry out attacks.
Russian warships in the eastern Mediterranean Sea on Wednesday drove away a Dutch submarine shadowing the squadron, the military said.