Potentially the best result emerging from the recent Syrian peace conference in Astana, Kazakhstan, is the agreement of Turkey, Russia, and Iran to oversee a reduction of hostilities in northwestern Syria. Such an outcome would mitigate a humanitarian catastrophe, enable nationalistic Syrian rebels to separate themselves from al-Qaeda's Jabhat Fatah el-Sham （JFS）, and perhaps set the stage for useful, all-Syrian negotiations in Geneva.
Astana was about Moscow, Ankara, and Tehran trying to consolidate a common approach to calming and ultimately ending the Syrian crisis. The three parties have differing motives. Are they operationally compatible？
Russia's President Vladimir Putin took full advantage of American foreign policy failure in Syria to bolster himself domestically and occupy center stage in Syria, both militarily and diplomatically. The point Putin was able to make to the Russian public was critical: we have defeated an American-abetted attempt at regime change and we are back, after decades of humiliation, as a great power.
Surely Putin has given some thought to what might come after a successful military campaign. Taking a lesson from American failures in Iraq in 2003 and Libya in 2011 – and perhaps from one unfolding now in eastern Syria – Russia knows about the importance of post-conflict stabilization. Although armed conflict continues at decreased levels, Moscow now seeks diplomatically to consolidate the military gains secured by its air campaign in coordination with Iranian-directed ground operations involving Shia foreign fighters mainly from Lebanon, Iraq, and Afghanistan.
For Tehran, the uniqueness of the Assad regime is its willingness to subordinate itself completely to Iran on all matters related to Hezbollah. Hezbollah's ability to dominate Lebanon and threaten Israel depends, in Iran's view, on a secure Syrian hinterland and a compliant Syrian government.
Ankara has no interest at all in the Assad clique clinging to power in all or part of Syria. Syrians aside, Turks have paid the highest price for the sanguinary political survival strategy of the Assad regime. From Ankara's perspective Syria will remain in ruins, hemorrhaging humanity for as long as the regime exercises power.
If Ankara and Moscow are on the same page in terms of marginalizing Iran's Syrian tool, then Washington's support is merited and potentially important. For the Obama administration, getting and keeping a nuclear agreement with Iran dictated speaking loudly without a stick in Syria. Presumably the Trump administration – even if it elects to respect the nuclear accord – will not be so well-disposed toward Iranian domination of Syria.