The issue is expected to dominate a NATO summit set for Washington in April. NATO's mission has (changed) dramatically since its founding in 1949, a time when the West was intent on halting the westward spread of Soviet-led communism -- a threat Winston Churchill warned about in his famous  Iron Curtain  speech delivered on March 5, 1946, at Westminster College in Fulton, Mo., 130 miles east of here.  
 Verb: changed
No