All Islamic State-held territory in Syria has been “100 per cent” eliminated, the White House said today.
The US-backed Syrian Democratic forces have said ISIS has lost its last remaining bit of territory in Syria, bringing an end to its “calpiphate”.
The complete fall of the last IS stronghold in Baghouz would the end of the militant group's self-declared caliphate, which at its height stretched across large parts of Syria and Iraq.
It is claimed by officials that sporadic fighting continues on the ground between coalition forces and the group’s holdouts, however.
US President Donald Trump said "it's about time" after a campaign by US and coalition forces that spanned five years and two US presidencies unleashed more than 100,000 bombs, and killed untold numbers of civilians.
US officials said the Syrian Democratic Forces are still battling the last remaining IS fighters who are holed up in tunnels along river cliffs in Baghouz and have refused to surrender.
Officials said the SDF has not announced any declaration of victory, and there was no announcement planned.
According to the officials, the SDF is moving slowly and carefully, and is willing to wait out the IS fighters who are out of food and low on water.
White House press secretary Sarah Sanders told reporters aboard Air Force One that Mr Trump was briefed about the development by acting defence secretary Patrick Shanahan.
Mr Trump showed reporters a map of Iraq and Syria that showed that the terror group no longer controlled any territory in the region.
"Here's ISIS on election day," he said, pointing to a red area signifying the group's previous territorial gains, and then to one without any red: "Here's ISIS right now."
He has been teasing the victory for days, most recently on Wednesday when he said the milestone would be achieved by that night, but sleeper cells of fighters have re-emerged.
British forces will not scale-back their presence in Syria and Iraq following the capture of the last remaining territory held by the so-called Islamic State, it has been confirmed.
Major General Chris Ghika, Deputy Commander of the Global Coalition's joint task force, said the terror organisation is by no means "leaderless or rudderless", despite its loss of physical territory.
But he said he could not predict whether the fall of the physical territory would substantially increase or decrease the terror risk to the UK.
Maj Gen Ghika told reporters at a Ministry of Defence briefing ahead of Baghouz's fall: "There are no plans to scale down the contribution to Operation Shader."
He added: "The US have said they are going to keep a presence in northern Syria so air power will play an important part in that, and we expect the British contribution to keep going on that side.
"In Iraq exactly the same maxim applies, the British troops that are training the Iraqi security forces are going to stay and keep doing what they are doing... because Isis continues to present a threat and that threat is met largely by the Iraqi security forces."
Maj Gen Ghika said the coalition must remain "very conscious" about the continued threat of IS and warned against allowing Syria to become a "safe haven" for the ideology.
He continued: "They are not leaderless or rudderless. One of the reasons why even after the end of the physical caliphate ISIS will remain a dangerous organisation is because there are members of the organisation willing to take on the struggle.
"They are less experienced, they are less capable...than the people of years ago... so the organisation is weaker but there are still people willing to take on the leadership function...and that is one of the things that we target."
Maj Gen Ghika estimated there were a few hundred IS fighters in eastern Syria, and between 1-2,000 in Iraq.
Additional reporting by Press Association