What makes the Syrian Civil War (2011-present) rather unique compared with cases of foreign fighters in the past

It is unique due to the presence of large a number of foreign fighters.

Explanation:

The Syrian Civil War is unique as compared with cases of foreign fighters in the past because in other civil wars that occurs in the past, very less quantity of foreign fighters take part in the war while in Syrian Civil War, a large quantity of foreign fighters join the war. In this war Iran and Russia support the Syrian government while Turkey, United states and many European countries supported the rebels.

the soviet union wanted to impose communist governments in eastern europe.

it allows shippers to carry commercial goods, which allows them to save time and money.