The Syrian crisis, which has been often described as a proxy war between NATO and Russia, has lasted for more than 10 years with no visible sign of an end. Most scholars explain the reasons behind NATO’s and Russian intervention with realistic motives. However, there are cases difficult to explain only from a realist perspective. For example, great power diplomatic efforts to remove chemical weapons and adopt sanctions at the cost of energy interests. These actions can be viewed as humanitarian involvement. The study argues that great powers’ motivation cannot be judged uniformly, but their actions should be evaluated separately, as some actions might be realist and some humanitarian, and some a mixture of both. Therefore, the purpose of this paper is to examine the reasons behind great powers’ involvement in the Syrian crisis by examining key decisions each power took during the war, from both aspects: realist and humanitarian. The study begins by outlining the theoretical background behind both perspectives and establishing criteria for judging a decision as realist/ humanitarian. This has been applied in reviewing the context behind five key decisions NATO (the US and European allies) and Russia made during the crisis. The study finds that one time all parties acted in a realist fashion, which produced no significant outcome. Contrary to this, one time all parties acted on humanitarian motives, which resulted in a favorable outcome. In the case when two parties, the US and Russia, acted as a realist, and the EU as humanitarian power, the EU’s efforts were insufficient to produce a favorable outcome. In other cases, when two parties, the EU and the US, pursued humanitarian motives, and Russia realist, the result depended on whether Russia pursued them actively or non-actively. In the former case, the result was ineffective to prevent further atrocities, whereas in the latter favorable outcome was still possible.