US-backed and Kurdish-led Syrian forces have launched a final push to defeat the ISIS group in the last tiny pocket the extremists hold in eastern Syria.
Syrian Democratic Forces spokesman Mustafa Bali tweeted the offensive began on Saturday (local time) after more than 20,000 civilians were evacuated from the ISIS-held area in the eastern province of Deir el-Zour.
An SDF statement said the offensive was focused on the village of Baghouz.
The SDF, backed by US air power, has driven ISIS from large swathes of territory it once controlled in northern and eastern Syria, confining the extremists to a small pocket of land near the border with Iraq.
Scores of ISIS fighters are now besieged in a small area consisting of two villages, or less than once percent of the self-styled caliphate that once sprawled across large parts of Syria and Iraq.
In recent weeks, thousands of civilians, including families of ISIS fighters, left the area controlled by the extremists.
'The decisive battle began tonight to finish what remains of Daesh terrorists,' Mr Bali said, using an Arabic acronym to refer to ISIS.
US President Donald Trump predicted on Wednesday that ISIS will have lost all of its territory by next week.
'It should be formally announced sometime, probably next week, that we will have 100 percent of the caliphate,' Mr Trump told representatives of a 79-member, US-led coalition fighting ISIS.
US officials have said in recent weeks that ISIS has lost 99.5 percent of its territory and is holding on to fewer than five square kilometres in Syria in the villages of the Middle Euphrates River Valley, where the bulk of the fighters are concentrated.
The Britain-based Syrian Observatory for Human Rights said since the SDF began its offensive against ISIS in the area on September 10, about 1279 ISIS gunmen and 678 SDF fighters have been killed.
It said 401 civilians, including 144 children and teenagers, have been killed since then.
Earlier on Saturday, ISIS militants attacked SDF fighters near an oil field in the country's east, triggering airstrikes by the US-led coalition.
The Observatory said 12 ISIS gunmen attacked the SDF and clashed with them for several hours until most of the attackers were killed early on Saturday. It said 10 attackers were killed, while two managed to flee.
Other activist collectives, including the Step news agency, reported the attack, saying some of the attackers used motorcycles rigged with explosives.