The monroe doctrine signaled a more active role in especially within the americas.

President Monroe passed the Monroe Doctrine because he was afraid of too much European involvement in Middle and South America. The US feared new involvement of European powers in the Americas -- first of France after Napoleon's victories, then of the Allied powers after Napoleon's defeat who had sworn to uphold, if necessary, by force, the power of monarchs wherever it was threatened. The Monroe doctrine expressly excluded the already existing involvement of Europe's colonial powers, but it drew the line there: every new 'colonial' effort or any armed intervention to change or forcibly retain the status quo would be actively resisted by the USA.