This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...en. Whether a free nation chooses to do so or not is a matter of its own self-interest, not of respect for the nonexistent “rights” of gang rulers. It is not a free nation’s duty to libera
te other nations at the price of self-sacrifice, but a free nation has the right to do it, when and if it so chooses.
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This right, however, is conditional. Just as the suppression o
f crimes does not give a policeman the right to engage in criminal activities, so the invasion and destruction of a dictatorship does not give the invader the right to establish another variant ...