President Barack Obama and counterterrorism officials said Friday that U.S. officials had broken up a terrorist plot to attack cargo planes in the U.S. and two Jewish sites in Chicago. Officials said a new arm of al Qaeda, known as al Qaeda in the Arabian Peninsula, was responsible for the plot. "Going forward, we will continue to strengthen our cooperation with the Yemeni government ... to destroy this al Qaeda affiliate,” Obama said in a press conference. Packages containing explosives were discovered in Dubai and the East Midlands airport in Britain; he said that flights in Newark and Philadelphia were checked as precautions, though he did not say anything about the commercial plane that was escorted by fighter jets to JFK. Officials said these packages originated in Yemen. Several members of al Qaeda in the Arabian Peninsula have been arrested in other plots, and the U.S. donated $150 million to help Yemeni forces fight the group.