An invasion is what it's called when a military force goes into action in a foreign country with the aim of overthrowing the people in control. The D-Day invasion for example.

Afghanistan last year was an invasion every bit as much as the Soviet invasion was. More so in fact, since that could reasonably be seen as an attempt to bolster up a government in control.

When Vietnam went into Cambodia to overthrow Pol Pot that was an invasion, and a good thing to happen, since Pol Pot's regime made the Taliban and Saddam look like pussy-cats. In spite of which the US and other countries continued to support Pol Pot, and punished Vietnam for overthrowing his regime, with extended sanctions and blockages on humanitarian aid.

Though it is a good thing that the Taliban and the type of repression they were involved with are no longer in control in at least part of Afghanistan (at a pretty terrible price), I think it's very doubtful whether any significant damage has been done to the ability of people who share Bin Laden's ideology to carry out atrocities around the world.

Paradoxically, it seems possible that the invasion of Iraq has provided such people with an operating base and even a kind of safe haven which is if anything more useful than Afghanistan.

If you kick over a beehive you do not get rid of the danger if getting stung as you go about your gardening. Not even if you take a few hundred bees unto custody.