Today's bombing - the eighth in Russia in less than three months - underscored the deadly increase in terror tactics by guerrillas fighting for Chechen independence.
The bombing underscored the increasing vulnerability of American troops to terrorists even in the most secure allied countries.
Indeed, the bombing underscored how insecure Baghdad still is, more than three months after the end of the war.
The bombings, which devastated both embassies, underscored the vulnerability of American personnel and property in an age of global terrorism.
But the bombings only underscored the challenge he faces in trying to inspire public confidence as sectarian violence continues.
Standing near the ruined bus, Representative Jerrold Nadler, a New York Democrat, said the bombing underscored the "hypocrisy" of the hearings in The Hague.
Yesterday's deadly bombing of a Kurdish party's offices just beyond the American occupation headquarters underscores the pervasive insecurity and sectarian divisions.
Both bombings, as well as chronic kidnappings, underscore the lawlessless in the Caucasus more than two years after the end of the bloody Chechen war.
The bombings have also underscored the tensions that rest just beneath the surface here, where anxiety and fear exist side by side with the images of a democratic election process.
The bombing was the fifth in Russia in less than three weeks and underscored how vulnerable Russia remains to terrorist attack, even with heightened security.