na-adjective
nationalistic; ultranationalistic
Describes attitudes, policies, or movements that emphasize national essence and often extreme patriotism. Can carry a critical or historical tone.
彼の国粋的な主張は、時に排他的に聞こえる。
His nationalistic arguments sometimes sound exclusionary.
国粋的な教育政
The ultranationalistic education policy is causing controversy.
愛国的 means 'patriotic' in a generally positive sense, whereas 国粋的 often implies a more extreme or exclusionary nationalism.
Derived from 国粋 (national essence) + 的 (-like, -istic). 国粋 itself is a Meiji-era coinage combining 国 (country) and 粋 (essence, purity).