Answer:
By stressing out that in the case of certain need the United States will have the possibility to react and intervene in the countries of Latin America, thus spreading their influence in this region.
Step-by-step explanation:
This is important because with the Monroe's doctrine States put a stance that no European country should interfere in the political changes of American continent. Also, that meant that United States won't interfere in Europe. Roosevelt tried to spread influence of the States by proclaiming the Corollary.