During the first presidencies of Vladimir Putin , who assumed the top office , first as acting president , on the last day of 1999 , and United States president George W. Bush , the United States and Russia began to have serious disagreements . Under Putin , Russia became more assertive in international affairs ; under Bush , the U.S. took an increasingly unilateral course in its foreign policy in the wake of the September 11 attacks
September 11 attacks
September 11 attacks
Russia–United States relations