A Republican U.S. senator lambasted the White House on Monday for **t sending a top American official to a Paris unity march after deadly Islamic militant attacks in that city, and a New York tabloid headline screamed "You let the world down." The image of Israeli President Benjamin Netanyahu and Palestinian leader Mahmoud Abbas flanking the leaders of France, Germany and Mali dominated coverage of Sunday's unity march and highlighted the Absence of President Barack Obama or other senior U.S. officials. French President Francois Hollande and 44 foreign dignitaries headed more than a million people in a march called to show solidarity after Islamist militants killed 17 people in three days of attacks in the French capital last week. The United States was represented by its ambassador to France, Jane Hartley. A senior U.S. administration official cited security requirements as a central reason why neither Obama **r Vice President Joe Biden made the trip, saying their security needs can be distracting from such events.