Very simple - apart from everything else, Putin knows the bottom...

Very simple - apart from everything else, Putin knows the bottom line is that Islam is the overarching long term problem and enemy.  However, as much as Islam is the ultimate enemy, politics is as much about 'the now' as it is about the mid to long term.  For various reasons, the Middle East has always been extremely strategic geopolitically to Russia (and former USSR) because of access via Syria to Mediterranean.  The Russian Naval base in Syria (though small, but being upgraded), is geopolitically considered to be just about their key port outside of Russia.  The Mediterranean provides Russia, potentially an access point to Southern Europe, Africa and beyond.

Further, Iran is also strategic to Russia for a number of reasons, but particularly because it gives them virtually free access through to Syria and also because Iranian ports (potentially) give Russia potential access to the Indian Ocean (via the Arabian Sea).

Iran and Syria (being Shia controlled) provides Russia with one geopolitical side of the coin (of the Middle East), while the Turks (Sunni) being on the EU and Western geopolitical side together with the other Sunnis (Shia competitors) on the opposite side of the coin.

Israel represents a powerful speck of sanity amongst the insanity in the Middle East, but held hypocritically accountable by its judaphobic detractors for daring to respond and deal with its enemies (the Islamic nutjobs) in kind, who in turn, are hypocritically not in question by the same detractors.

When push comes to shove and human nature is considered, Russia and Israel have far more in common (to the ire of the judaphobes) than either have with their Islamic neighbours.

Back to Russia, one does not need to be a rocket scientist to understand it's geopolitical drivers:



Then add the delicate global energy situation (Oil in freefall - it's impact on Russia, Sauds etc with another player Iran coming online) together with Natural Gas and other energy, with balances and needs shifting and though this is another complexity, this is still all about geopolitics.

Europe (historically, Democratic) and land-linked to Russia (historically Communist, but presently Putinist), which is land-linked to the Middle East (symbollically Islamic and crazy), with USA (symbolically Democratic) and allied with Europe.  Israel, a stick in the mud for Islam and a convenient excuse for some other's issues.