Russia supports the regime of President Assad and believes that the regime is crucial for a unified state. They cover military and economic needs of Syria.
Russia has a treaty of amity and cooperation with Syria containing 15 articles that was signed on October 8, 1980.
America supports Kurds and other rebel groups on the opposing side of Assad and Russia. They give military support to rebels with troops in Syria. It is turning into a Russia-US conflict as well.
Russia bombs Syria in what they say is an attempt to defeat ISIL, however few of the bombings have actually been directed at ISIL.
The Syrian Crisis of 1957 was a period of diplomatic confrontations between Syria and the S.U. agianst the US and Turkey. Turkey sent troops to the border between Syria, so the SU threatened to launch missiles at Turkey, causing the US to threaten to attack the SU if missiles were launched on Turkey.