Police and protesters prep for NATO summit

Some 25,000 French and German police - and perhaps as many protesters - are taking up positions around three cities on both sides of the Rhine before a NATO summit involving President Barack Obama and 25 other leaders.

[Tooth4U]

NATO was created during the Cold war as a unifying block against the Soviet Union.

When the Soviet Union collapsed NATO according to its own charter no longer had justification to exist. So, why does NATO exist post the Soviet era?