The US experienced major foreign policy issues in the late 1800s with who?

In the late 1800s, the United States faced significant foreign policy issues primarily with Spain and in relation to its expanding influence in Latin America and the Pacific. The Spanish-American War in 1898 marked a pivotal moment, resulting from tensions over Cuba's struggle for independence and leading to U.S. territorial acquisitions like Puerto Rico, Guam, and the Philippines. Additionally, the U.S. began asserting its presence in Asia, particularly through the Open Door Policy in China, reflecting its growing imperial ambitions.