Question

1. an informal policy known as the __________________________ warned european countries against interfering in the western hemisphere.

Explanation:

The question is about a historical policy related to U.S. foreign policy that warned European countries against interfering in the Western Hemisphere. The Monroe Doctrine is the key policy here; it was an informal (later became a significant) policy stating that European powers should not colonize or interfere in the Americas, and the U.S. would stay out of European affairs.

Answer:

Monroe Doctrine