Let's not blow out of proportion that President Putin is in Cuba.   It's more of a finger in the eye to President Obama than a return to the days when Soviet troops were stationed in Cuba.
 
However, Cuba and Russia did agree on one thing, as reported by The New York Times:

Russia has decided to reopen an electronic eavesdropping post in Cuba that it closed more than a decade ago, reaching out for a onetime symbol of its global superpower status, Russian officials and newspaper reports said on Wednesday.

President Vladimir V. Putin agreed with Cuba’s leader, Raúl Castro, during a visit to Cuba last week to reopen the post. In exchange, Mr. Putin agreed to forgive about 90 percent of Cuba’s Soviet-era debt to Russia, or about $32 billion. News of the debt relief emerged last week, but the agreement to reopen the listening post was first reported Wednesday by the Russian newspaper Kommersant.

Let's understand what this is.   Putin has been emboldened by Obama's weakness and he is just showing it, 90 miles from Florida.  He is also going around Latin America projecting power and doing it because he senses that the US has walked out of the region.
 
It doesn't change the military balance.  It's just bad optics for a President Obama who doesn't need more of it.
 
P. S. You can hear CANTO TALK here & follow me on Twitter @ scantojr.