Ever since Christmas, when a Nigerian man allegedly tried but failed to blow up a jetliner bound for Detroit, officials have been even more cautious in monitoring the skies. Yesterday was one of those days. A diplomat from the oil-rich Middle Eastern nation of Qatar, a U.S. ally, apparently tried to enjoy a smoke in a Denver-bound plane's bathroom, triggering a bomb scare serious enough that NORAD scrambled to procure jet fighters. The envoy in question, Mohammed Al-Madadi, "was traveling to Denver on official embassy business on my instructions, and he was certainly not engaged in any threatening activity," reads a statement on Qatar's Washington embassy Web site (via The Associated Press ). No explosives were found, and authorities speaking on condition of anonymity say they don't think Al-Madadi was trying to hurt anyone. Initial reports indicated that a man might have attempted to ignite his shoes during United Flight 663, a Boeing 757 carrying 157 passengers and six crewmembers that landed at DIA just before 7 p.m., wrote The Denver Post . An official suggested there may have been a "misunderstanding" after Al-Madadi, traveling from Ronald Reagan Washington National Airport, responded to a federal marshals' questioning, notes The Washington Post .