Many folks don’t know that the Monroe Doctrine had two parts. We promised not to interfere in Europe. And we warned Europe not to interfere in the Americas.
We’ve ignored the first part for quite some time now. So as you noted, why shouldn’t Russia ignore the second part?
The first part was ignored by Europe (mainly Germany), not us.
And didn’t Kerry declare the entire doctrine to be “over” when he was Obama’s SOS?
Germany had no colonies in the Western Hemisphere, our “allies” Britain and France did.
Look to see a Russian airbase in Cuba soon as well as a Naval Base in Nicaragua. You will know its bad where they build Russian Orthodox Churches in these lands. A Russian rocket or two in Nicaragua could shut down the Panama Canal.