"The campaign to defeat ISIS is now in a new phase in Iraq and Syria", Col. Robert Manning, a Pentagon spokesman, said, using an acronym for the Islamic State.
However, the Russian Ministry of Defense said Monday that it had begun working with Arab and Kurdish groups operating east of the Euphrates River, an area of operations for the United States advisers and the US-backed Syrian Democratic Forces, highlighting an increasingly complex battle space. As part of that effort, the Pentagon announced in August it had about 3,000 more troops in Afghanistan than acknowledged under then-President Barack Obama.
Pentagon spokesman Eric Pahon announced on Tuesday that the U.S. intends, as a matter of policy, to keep ground troops in Syria "as long as necessary", irrespective of the fact that ISIS, the group they were initially deployed to fight, has nearly no territory left in the country. US forces in Syria and Iraq are "trending downward", he added, without specifying whether the 2,000 troops in Syria included the 400 Marine artillerymen that the Pentagon announced last week would soon leave the country.
British fighters who had fled to other countries would also be found and stopped from returning to the United Kingdom, he said, adding that there would be no "safe space" overseas for them either. He said the campaign to defeat IS is now in a new phase in these countries.
At least 800 Britons have gone to Syria and Iraq to fight for IS and 130 of those have been killed in conflict.
"To ensure an enduring defeat of ISIL, the coalition must ensure it can not regenerate, reclaim lost ground, or plot external attacks", he said.
"We are going to maintain our commitment on the ground as long as we need to - to support our partners and prevent the return of terrorist groups", Pentagon spokesman Eric Pahon told AFP.
Coalition forces are still needed in the two countries, Manning said, adding that they will now focus on "train, advise and assist" missions.