mr. obama spoke with british prime minister david cameron, king abdullah of jordan, and the prime minister of turkey, emphasizing that democracy will bring more, not less, stability to the region. >>> and this country's top military officer left for the middle east today. admiral mike mullen, chairman of the joint chiefs, will meet with jordan's king abdullah and prime minister benjamin netanyahu of israel to reassure them of u.s. support. >>> and a program note. david gregory will have much more on the revolution in egypt tomorrow on "meet the press," and as congress prepares to take on major legislation, a sunday exclusive with house speaker john boehner. that's tomorrow morning here on nbc. >>> when "nightly news" continues this saturday evening, a deadly explosion raises new questions about the safety of america's gas pipelines. we'll be right back. >>> there are new questions about the safety of this country's gas pipelines, millions of miles of them, after a series of explosions this week, including one in pennsylvania that left five people dead. nbc's tom costello has more tonight.