PHNOM PENH, Nov 12 (AFP) - The White House on Saturday hailed what it said appeared to be an "extraordinary victory" for Ukraine in recapturing the city of Kherson from Russian occupiers.

"It does look as though the Ukrainians have just won an extraordinary victory where the one regional capital that Russia had seized in this war is now back under a Ukrainian flag -- and that is quite a remarkable thing," National Security Advisor Jake Sullivan told reporters as he accompanied President Joe Biden to the ASEAN summit in Cambodia.

Sullivan was speaking after Ukrainian troops entered the city, which was one of the lynchpins in Russia's occupation of swathes of Ukraine.

Sullivan said that the Russian retreat would have "broader strategic implications," including relieving the longer-term threat by Russia to other southern Ukrainian cities such as Odessa.

"It's a big moment and it's due to the incredible tenacity and skill of the Ukrainians, backed by the relentless and united support of the United States and our allies," Sullivan said.

Asked about reports that the Biden administration has started to press President Volodymyr Zelensky to explore negotiations with Moscow, Sullivan said that Russia, not Ukraine, was the side that has to decide whether or not to go to the table.

"This whole notion, I think, in the Western press of 'when's Ukraine going to negotiate?' misses the underlying fundamentals," Sullivan said.