Imperialism is a term used to describe the policy of powerful countries or empires seeking to extend their influence and control over weaker nations or territories. As such, antonyms for "anti-imperialism" would be concepts that advocate for the opposite approach, such as imperialism itself or colonialism, annexation, or expansionism. Other possible antonyms could be words that reflect a non-interference or non-interventionist stance towards the affairs of other countries, such as isolationism, non-interventionism, neutrality, or nonalignment. Finally, words like globalization or multiculturalism could be considered antonyms from a different perspective, as they reflect a more interconnected and integrated view of the world.