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: Airplane Terror Attempt Not Part of Larger Plot U.S. Homeland Security Secretary says it would be inappropriate for her to speculate on whether the suspect had ties to al-Qaida as he has claimed VOA News 27 December 2009 U.S. Homeland Security Secretary Janet Napolitano says there is "no indication" that Friday's attempted attack on a U.S. airliner was part of a larger terrorist plot. Napolitano told U.S. news network CNN Sunday that an investigation is ongoing. In a separate interview with ABC News, Napolitano said it would be inappropriate for her to speculate on whether the suspect, 23-year-old Nigerian Umar Farouk Abdulmutallab, had ties to al-Qaida as he has claimed. U.S. authorities have charged Abdulmutallab with trying to blow up an airliner as it approached the midwestern U.S. city of Detroit. The suspect is listed in a U.S. government intelligence database, but he was not on the "no-fly list" that would ban him from boarding the flight, which originated in Amsterdam. White House Press Secretary Robert Gibbs told ABC that the incident has prompted officials to review procedures for placing potential terrorists on watch lists, and to reevaluate security systems at airports. U.S. authorities have begun to take additional security precautions for domestic and international flights. A preliminary analysis by the Federal Bureau of Investigation said the suspect was trying to detonate an explosive called PETN. Instead of exploding, the device started a fire. Abdulmutallab was overpowered and detained by other passengers and crew members. Officials say Abdulmutallab told them he had received training for the attack from al-Qaida operatives in Yemen. Charges were read against him Saturday in a Michigan hospital where he is being treated for burns he suffered during the incident. Officials say Abdulmutallab began his trip in Nigeria. But the Nigerian government says the suspect had been living outside the country for some time. Nigeria's information minister, Dora Akunyili, told reporters Sunday that Abdulmutallab snuck into the country Thursday, the day before the attack, and left the same day. Nigerian officials say they have launched their own probe into the incident, and that they are working with U.S. investigators. Some information for this report was provided by AP, AFP and Reuters. .