Russia is the “rock,” Iran is the “paper,” and the United States is the “scissors”…
Iran’s strategy is to envelope Syria like a piece of paper, topologically combining Iran’s Iraqi “paper,” along with Iran’s Hezbollah/Lebanon “paper” to form a patchwork-quilt Shiite Empire spanning from Iran/Persia through Iraq, and Syria, and Lebanon into the Mediterranean Sea.
As an example of this, Iran just announced it was to build a trans-Iran/Iraq/Syria/Lebanon railroad.
Russia is the “rock” trying to bash the Sunni opposition to pieces in order to carve-out its eastern Mediterranean naval outpost and military enclave.
The United States, through Sec of Def Mattis, under the strategic cover of defeating ISIS in Eastern Syria is the “scissors” against Iran’s “paper” Shiite Empire.
The United States with its indigenous allies is trying to efficiently occupy eastern Syria from the Kurds in the north to Jordan in the south. By topologically “cutting” off Iran’s patchwork piece of paper, Iraq, from Iran’s patchwork piece of paper, Syria, the United States is attempting to defeat Iran’s waxing paper Shiite Imanate.
Before Iran’s chemical attack in the name of Assad, the western Syrian rock strategy of Russia, and the eastern scissors strategy of the United States were avoiding each other, complementing each other, and together quietly weakening the whole Syrian paper envelopment strategy of Iran. This was great for Russia and the US, but bad for Iran. Iran saw the United States’ cutting its patchwork-quilt in two in eastern Syria as an existential threat to the grand strategic arc of its contiguous Mesopotamian/Levantian/Mediterranean swatch of Empire.
Therefore, Iran had to do something to instigate a hot war between the United States and Russia. And presto, Iran bombs civilians with Sarin using Assad’s planes, Assad takes the fall, and Russia and the United States are escalating against each other.
Russia and the United States urgently need each other to thwart Iran’s scheme to control the Middle East. It is in both Russia’s and United States’ worst strategic interests to allow Iran to become the colossus of the Middle East. Syria is big enough for Russia and the United States to find a modus vivendi and live with each other, allowing each to achieve strategic goals.
Russia and the United States have a mutually exact goal i- both aim to defeat the ISIS Sunni Caliphate and the Iranian Shiite Imanate. To defeat both Islamic radical terror threats requires Russia and the United States to work together, and not fight each other.
In the current war against both Sunni and Shiite radical Islamic terror, the United States and Russia are critically necessary for one another as allies, not inimical enemies.