To explain their empire and concur more land
There were lots of foreign changes that presented challenges for the US. I'll give you a few examples from different time periods. First would be when England wanted to tax the Americans in the Revolutionary period. They did this to try and restrict America's freedom. Another example would be that Russia had spies during the cold war period. This was to gain intelligence of the US war plans. Also when Germany sent the Zimmerman Telegram to Mexico during the WWII period. This was to get Mexico to launch a surprise attack on the US.
It came from Texas that is all I know sorry
The Monroe Doctrine was drafted because the U.S. government was worried that European powers would encroach on the U.S. sphere of influence by carving out colonial territories in the Americas
