Moscow will halt military steps in Ukraine - only after a US guarantee not to post missile shield there

... according to our US and Russian sources, Putin is after hard, practical strategic gains, principally, a demilitarized Crimea that would not threaten Russia from its western doorstep.
In fact, the Russian president has couched his demands for further negotiations under four headings:

1.  The Kiev government whichever form it takes must sign an obligation to abstain from any ties with NATO.
2.  Neither the US, NATO or any other power will deploy X-Band or BX-1 radar stations on Ukraine territory whether on land, sea or air. This guarantee would additionally cover elements of an anti-missile missile shield and ballistic missiles placing Russia in their sights.
3.  Restrictions will govern the types of weapons allowed the Ukrainian army.
4.  Local military bodies will be established to protect the Russian-speaking and ethnic Russian regions of Ukraine.

Putin emphasized in his conversation with Merkel that, until those four conditions are met, Russian forces would remain where they are in Crimea and if this was deemed necesssary, advance into other parts of Ukraine.

1. Ukraine should have the right to choose freely its economic and political associations, including with Europe.

2. Ukraine should not join NATO, a position I took seven years ago, when it last came up.

3. Ukraine should be free to create any government compatible with the expressed will of its people. Wise Ukrainian leaders would then opt for a policy of reconciliation between the various parts of their country. Internationally, they should pursue a posture comparable to that of Finland. That nation leaves no doubt about its fierce independence and cooperates with the West in most fields but carefully avoids institutional hostility toward Russia.

4. It is incompatible with the rules of the existing world order for Russia to annex Crimea. But it should be possible to put Crimea's relationship to Ukraine on a less fraught basis. To that end, Russia would recognize Ukraine's sovereignty over Crimea. Ukraine should reinforce Crimea's autonomy in elections held in the presence of international observers. The process would include removing any ambiguities about the status of the Black Sea Fleet at Sevastopol.