FACTBOX: Scenarios for Georgia's South Ossetia crisis

(Reuters) - Russia used troops and warplanes to counter a Georgian attempt to regain control of its breakaway South Ossetia region, and the two sides disputed control of the regional capital. Georgia called for an immediate ceasefire.

The following are possible scenarios:

* Russia may use its military might to impose a return to the status quo ante, forcing Georgia to accept the continued separatism of South Ossetia.

* Russia may annex South Ossetia, the majority of whose population have already been given Russian passports. Outside powers might object but could probably do nothing about it.

* Russia may make a large-scale incursion into Georgia and try to overthrow President Mikheil Saakashvili, whose pro-Western stance has annoyed Moscow since he won Georgia's presidential election in 2004. Neighbors and other world powers might object strongly, seeing this as a new expansionist drive upsetting the international order, but they could do little to stop it.

* Georgia, lacking the military strength to oppose the Russians, must decide whether to pull its troops out of South Ossetia in a humiliating climbdown or to continue resisting the Russian advance and appeal for outside help on the grounds that South Ossetia is still Georgian territory.

(Writing by Tim Pearce; editing by Mary Gabriel)