The United States is expressing concern over two bombings in Yemen that occurred over the last week --- one on Sunday that left four South Korean tourists dead and another on Wednesday against a South Korean government delegation.

State Department spokesman Robert Wood told reporters Wednesday that the two incidents are troubling and that involved parties are doing their best to determine the details behind the attacks. Wood expressed U.S. condolences for the South Korean victims.

The spokesman said Washington continues to work with the Yemeni government in trying to combat al-Qaida, who authorities believe was behind the bombings.

Wood said it’s important the international community becomes united in terms of trying to deal with threats from the terrorist organization.

He said such threats are not restricted to Yemen, but are present in many nations around the world. He suggested an intensified level of cooperation to fight al-Qaeda and other groups that practice terrorism.