Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. US Troops Find Possible Mustard Agent on Rocket Fragment by VOA News A U.S. military official said a rocket that landed near U.S. troops at a military base in northern Iraq may have contained a mustard agent. In a briefing, an official at the Pentagon told reporters no one was hurt in Tuesday's attack on the Qayara West air base, but several hundred U.S. troops were on the base at the time. The official called the attack "militarily insignificant." But he said a fragment of a rocket that landed inside the base was found to contain a black, oily substance on a fragment of metal. Initial tests indicated the substance might be a mustard agent, but a second test was negative. The official said the fragment has been sent to a lab for more testing. Two to four troops who had examined the fragment underwent decontamination after examining the shell, as a precautionary measure. The official said while there have been a number of instances this year in which chemical agents are believed to have been used against Iraqi, Kurdish, and Syrian forces, this was the first time such an agent had come close to U.S. forces.