Sure it is. Self defense and to help out the native population are easy arguments for the invasions.
The same cannot as easily be said for the Muslim invasion, since if their motives were truly to liberate them then they would have let the natives Egyptians (and Persians, Spaniards, etc.) rule themselves. Instead they imposed their own rule and enriched themselves, while the Americans at least can point to their helping the Iraqis and Afghans set up their own governments instead of making Iraq and Afghanistan a part of the United States.
I know that Muslims like to believe their history of conquering was a string of liberations, but that is from a biased eye. Muslims of the time did not even try to convince people that the wars were for liberation. They admitted it was to spread Islam and to enrich Muslims. It was only later that Muslims attempted to rewrite history by claiming the wars were to liberate the poor people of any nation that happened to border them.
The real question is what the people of the time thought, not what their ancestors think over a thousand years later.