This Will Cheer Your Saturday

WASHINGTON — American counterterrorism officials are increasingly concerned that the most dangerous regional arm of Al Qaeda is trying to produce the lethal poison ricin, to be packed around small explosives for attacks against the United States. For more than a year, according to classified intelligence reports, Al Qaeda’s affiliate in Yemen has been making efforts to acquire large quantities of castor beans, which are required to produce ricin, a white, powdery toxin that is so deadly that just a speck can kill if it is inhaled or reaches the bloodstream. Intelligence officials say they have collected evidence that Qaeda operatives are trying to move castor beans and processing agents to a hideaway in Shabwa Province, in one of Yemen’s rugged tribal areas controlled by insurgents. The officials say the evidence points to efforts to secretly concoct batches of the poison, pack them around small explosives, and then try to explode them in contained spaces, like a shopping mall, an airport or a subway station. President Obama and his top national security aides were first briefed on the threat last year and have received periodic updates since then, top aides said. Senior American officials say there is no indication that a ricin attack is imminent, and some experts say the Qaeda affiliate is still struggling with how to deploy ricin as an effective weapon.