By Margarita Antidze and Matt Robinson
TBILISI (Reuters) - President Mikheil Saakashvili on Friday mounted a fresh defense of Georgia's assault on South Ossetia in August, denying accusations Tbilisi had been the aggressor in the disastrous war with Russia that ensued.
Under fire from opponents who say he walked into a war Georgia could not possibly win, Saakashvili defended his actions of the night of August 7 during televised testimony before a bipartisan parliamentary commission probing the war.
Saakashvili remains popular among voters, but Georgia's fractious opposition is using the five-day conflict and its consequences to mount a fresh challenge to the pro-Western president, who came to power with the 2003 "Rose Revolution."
Saakashvili's defense was aimed primarily at a domestic audience. Western states did condemn Russia's intervention, but have not disguised their dissatisfaction with Georgia's assault on the rebel region. NATO looks certain to again deny Tbilisi a roadmap to membership when alliance foreign ministers meet on Dec 2-3.
Saakashvili dismissed as "utter nonsense" testimony this week by Georgia's ex-ambassador to Russia, Erosi Kitsmarishvili, who said Tbilisi had been the aggressor having mistakenly convinced itself it had the blessing of the United States.
"We acknowledge and confirm ... that the Georgian government took the decision to undertake a military operation in order to offer resistance to a widescale Russian intervention, a widescale assault on a peaceful population," Saakashvili said.
Defense Minister David Kezerashvili told the commission on Thursday that Georgia attacked the rebel capital Tskhinvali on Aug 7-8 because Russian forces were pouring across the border and it was a matter of time before they began attacking Georgian-populated villages.
But at the time, there was no public statement from the Georgian leadership that Russian forces were invading. The shelling of Tskhinvali after a ceasefire of several hours and the subsequent ground assault was justified as a response to rebel shelling of Georgian villages.
Saakashvili repeated the claim made later that Russia had already invaded and forced his hand, recalling "the most difficult choice of my life." Russia says the claim is nonsense, and that it intervened in its ex-Soviet neighbor only to defend South Ossetian civilians.
"RED LINE"
"Our answer to the question whether we have undertaken military action is 'Yes'," he told the commission. "It was a difficult decision, but it was an inevitable one."
"It's the responsibility of any democratically elected leader to defend his country, borders and peaceful population," he said. "I couldn't believe they (Russia) would cross that red line, I couldn't believe they would be first to take this step."
The war that ensued piled pressure on already strained relations between the West and Russia and deepened concern over the security of the Caucasus as a transit route for oil and gas to Western markets, bypassing Russia.
There had been skirmishes for months in South Ossetia, a pro-Russian region which threw off Tbilisi's rule in 1991-92.
Russia's counter-strike to the Georgian assault of August 7 drove the Georgian army out. Moscow's troops then pushed further into Georgia, saying they needed to prevent further Georgian attacks, but withdrew in October.
The West condemned Russia's "disproportionate response," but shied away from imposing sanctions on what for many European states is a vital energy supplier.
Moscow recognized South Ossetia and Georgia's other rebel region, Abkhazia, as independent states.
Georgia says 228 Georgian civilians and 169 military personnel were killed, while tens of thousands of Georgian refugees have yet to return to their homes.
(Editing by Giles Elgood)