Do the ends justify the means?

It's a question that we've been asking ourselves for a long time no with no clear answer. It's a question that is brought up in politics and ethics a great deal. We can ask this question to many situations today such as Iraq and Afghanistan. For example, most people would agree that Saddam Hussein and his sons were bad people. While we didn't go into Iraq with the explicit intent of getting rid of Saddam, does what we have done there justify getting rid of him and replacing the government that is similar to our own? In other wards, is Iraq better off now or when Saddam was in power? Also, moving to Afghanistan, many people would agree that the Taliban was and is a very oppressive group. Of course we went into the country to route out terrorist organizations, and many would argue that the Taliban is a terrorist organization or sorts, but does getting rid of them and replacing the government with essentially a puppet democratic government justify not only what we did there by getting rid of the Taliban? The simple answer may be yes, but in almost ten years of fighting, has the end truly justified the means? Has removing Saddam and his sons and going into Iraq under false pretenses as well as getting rid of the Taliban really justify going into the countries and replacing them with governments similar to our own and that we can get along with?