Russia decided to partially withdrawal its troop from Syria due to Moscow's disappointment over failures by pro-regime Iranian and Hezbollah forces to achieve victories against opposition forces fighting to topple the Assad government, the Saudi news-site Elaph reported Monday night.According to the report, Russia had been concerned about air support and bombed regions where Iranian and Hezbollah troops were located to face off Syrian opposition elements and Islamic State militants. However, Russia reportedly did not receive mutual coverage on the ground. The report added that disagreements between Moscow and its allies embattled in Syria ran so deep that Russian President Vladimir Putin announced, without warning, his plans to pull his troops out of Syria."The division of opinions between Russia and Iran and Hezbollah were stronger than (the Russian's) pact with the Syrian regime, which led to the Russian pullout," the report cited a source as saying. "In addition, the coordination between Russia and the West in arranging a ceasefire and negotiations in Syria contributed to the downsizing of forces. Iran and Hezbollah got an unhappy surprise from this coordination."Dropping AssadThe sources highlighted three reasons which contributed to the disagreement between Russia and the Shi'ite axis. The Russians rejected the strategic view of the Iranian regime, that the regime of President Bashar al-Assad is the protector of the Shi'ites in Syria and Tehran's interests in the region, especially against the Gulf countries.Additionally, the Russians rejected Iran's intentions to transfer advanced weaponry to Hezbollah in Lebanon, while Moscow was reportedly willing to give up on Assad as part of future agreements. The second reason was the Kurds. While Iran sees the growth in strength of the Kurds in the region as a threat to its internal stability - around three million Kurds live in Iranian territory - Russia supports Kurdish independence, since they have been the most effective and trustworthy fighters against ISIS.The third reason is the failure of Iran and Hezbollah to achieve significant military victories, including the expansion of the battlefronts in Tadmor and al-Raqqa, and against ISIS in the east towards the Iraqi border. "Iran is worried by the possibility of clashes with ISIS on its border with Iraq," explained the source. "Russia received assurances from its allies that there would be swift victories, however despite this there have been 1,500 Hezbollah and Iranian deaths on the battlefield, and another 5,000 injured."