In order to topple the Taliban, the Afghanistan invasion was a justifiable move. It produced results and now the Afghan people have freedom from oppression to look forward to. However, the United States needs to leave the country completely to sort out its own affairs. Only then will Afghanistan experience major change.
No, invasion of Afghanistan was not justified by over throw of Taliban government. The only reason that success had happened was the result of a knee-jerk reaction by the presidency due to a catastrophic event on the country that resulted in the deaths of millions of its citizens. There was no strategy developed when war was declared to get in and to exit when appropriate. Therefore no justification can come from success of "dumb luck."