Biden, in Visits to Middle East and Europe, Tries to Reassure Allies of U.S. Support.

ATHENS -- As he traded the political upheaval of the Middle East for the economic storms of Europe, Vice President Joseph R. Biden Jr. has preached a consistent message on his travels: ''The United States isn't going anywhere,'' as he put it on Sunday. It is a challenging, even far-fetched, argument to make at a time when the United States is pulling its last soldiers out of Iraq -- scrambling the calculus of players in the region -- and when it is not offering to rescue Greece or other debt-ridden European countries. [ABSTRACT FROM AUTHOR]