The Republicans were, of course, outraged that we would re-open our embassy in Cuba before they have taken solid steps toward democracy (ignoring the fact that we have embassies in dictatorships around the world).  To them, normal diplomatic relations and normal trade relations are a stick and carrot to use to coerce other countries around to our point of view (with military options always on the table for the worst offenders).  Change only comes in response to persistent U.S. efforts to force change or the other side cracking under economic pressure.

The Democrats, on the other hand, note that fifty years of sanctions and pretending that the Cuban government is not a “legitimate” government have not helped.  While there is no need to ignore the problems in Cuba, a U.S. presence in Cuba (beyond our continued lease on Guantanamo Bay which is if anything an offense to the average Cuban) gives us a greater opportunity to interact with all Cubans.  Cutting off diplomatic ties and closing embassies is not a tool to be used as a sanction (except in the most extreme circumstances), but rather is a security measure for our diplomats (i.e. why we still have not gone back to Iran).  Similarly, economic sanctions is a tool to be used to respond at very precisely calibrated levels to specific violations of human rights.  Engagement is what leads to change.

The question, of course, is which approach is more likely to result in change.  Do sanctions that isolate a country like North Korea (turning it into a fortress state with the average person having very little concept of life outside their home) make it more likely for reform to take place?  Or does full engagement with a country like China (with their top students coming to the U.S. for college and post-graduate studies before returning home) make it more likely that the regime will face internal pressure to reform?  The real problem with answering these questions is that we have very few countries that we have treated like Cuba and North Korea and Iran.  For most countries, including the old Soviet Union and its allies, we have used both approaches simultaneously — engagement along with some forms of economic and military pressure.  That leaves both sides able to claim credit for the results.