I fear that Assad is a .......smaller worry than some you might have.
Yes and no. War in Syria has ruined a huge country and led to millions of refugees in neighbouring countries and Europe.
"In 2016, the United Nations (UN) identified 13.5 million Syrians requiring humanitarian assistance, of which more than 6 million are internally displaced within Syria, and over 4.8 million are refugees outside of Syria.[31] In January 2017, UNHCR counted 4,863,684 registered refugees.[1] Turkey is the largest host country of registered refugees with over 2.7 million Syrian refugees."
On the other hand, militarily, North Korea seems a bigger danger, but will North Korea ever attack anyone? IMO, they are arming themselves to push the UN and US to lift sanctions.
Russia are the constant enemy, but they have long learned to fight their wars with the US/NATO by proxy. The main danger here is if they manage to break up NATO and the EU. This is a real possibility, and a reason why they are interfering with certain elections and referenda.
Then China. China are spreading themselves, but more like an underground forest fungus. They are offering "aid" and buying key companies around the world. They already exert significant influence, and probably will more, but more from a trade and economy perspective.