Hillary Clinton has a plan for defeating the Islamic State in Syria. Donald Trump has one, too. With the conflict in Syria spreading beyond its borders, it's essential to understand the new president's strategies -- and how they may need to be adjusted over the next four years.Mr Trump has advocated for a "safe zone" for Syrians to ride out the conflict. Such a zone would be a swath of territory inside the country, where today's refugees would reside instead of fleeing to Europe and elsewhere.