College American US american History Question

I’m working on a history multi-part question and need an explanation and answer to help me learn.

• Who were the leaders of imperialism/anti-imperialism; what were their views?
• What contributed to U.S. emergence as a world power?
• Are any of these factors still with us? What do you think? 
  • Note: We now face war in Ukraine, an expansionist Russia, Russian cyberwar against American infrastructure and attempts to undermine our democracy. We are coming back as a world leader, rebuilding our alliances especially NATO, and renewing our commitment to democracy. It is a new era in foreign relations and threats to our country. You are living at a historic time.