Manning announced the new official figure for American servicemembers in Syria on Wednesday, saying Defense Secretary Jim Mattis wants to increase transparency about where and how troops are deployed.
And the head of MI5, Andrew Parker, revealed in October that many of those who have travelled to Syria to support Daesh, the Arabic name for IS, also known as ISIL or ISIS, have already returned to Britain.
About 2,000 American troops are in Syria fighting the Islamic State, a Pentagon spokesman said on Wednesday, nearly four times the total previously disclosed as the Trump administration changes how troop numbers are publicly counted.
USA troops are known to be training and providing support to the Arab-Kurdish fighters of the Syrian Democratic Forces, who have been battling the Islamic State group in northern and eastern Syria.
Last month, the U.S. said there were only 503 USA troops in Syria and 5,262 United States troops in Iraq. He said the campaign to defeat IS is now in a new phase in these countries.
Wind warning for Donegal issued
A snow-ice warning for Ireland comes into effect this afternoon as Storm Caroline begins to pass close to the north-west coast. The weather will take a turn in the next 24 hours, and it's set to become bitterly cold for the next few days.
At least 800 people have left the United Kingdom to join ISIS in Iraq or Syria.
Syria is fully liberated from terrorists, all units of the Islamic State (IS) terror group (outlawed in Russia) have been destroyed, Chief of Russia's General Staff, General of the Army Valery Gerasimov, said at an annual briefing for foreign defense attaches yesterday.
Operations in both countries are shifting as the terrorist group shrinks, said Eric Pahon, another Pentagon spokesman.
"Important work remains to ensure lasting defeat" of ISIS, he said.
Coalition forces are still needed in the two countries, Manning said, adding that they will now focus on "train, advise and assist" missions.