In a surprise announcement, the Defense Department disclosed Thursday that U.S. officials have doubled the number of American troops in Syria to support the fight ISIS, an increase that predates the fall of Bashar al-Assad’s regime this month.  The Pentagon press secretary, Maj. Gen. Pat Ryder, said at the Pentagon briefing that the U.S. has roughly 2,000 troops deployed in Syria, even though the U.S. military and U.S. Central Command have consistently reported having only 900 troops there.  Ryder did not say when the number of U.S. personnel had increased. He said he had learned Thursday that the number has been significantly higher for some time.  “I don’t have a specific date to provide,” Ryder said, referring to the timing of the increase. “My understanding is it’s been for a while, so clearly before the fall of the Assad regime,” he said, adding, “At a minimum months.” “It’s been going on for a while,” he said. Ryder said the increase was not in response to the recent fall of the Assad regime or to the search for missing American journalist Austin Tice, who was kidnapped in Syria in 2012.  The additional U.S. troops are supporting the mission to defeat the Islamic State, also known as ISIS, and prevent it from regrouping, Ryder said. But he declined to provide more detail about what the U.S. forces are doing specifically, saying only that they are predominantly Army soldiers.  A defense official who asked not to be identified said the number of American forces in Syria may have been significantly higher than the Pentagon has reported for several years. The official said the true number of U.S. forces in the country may have been intentionally covered up. Ryder said a core group of 900 troops in Syria are on longer-term deployments, generally for nine to 12 months. An additional 1,100 have rotated into Syria on a temporary basis, for roughly 30 to 90 days.  Asked repeatedly why he announced the higher figure only now, Ryder reiterated that he had just learned of it himself. “Given that there is significant interest in Syria,” Ryder said, he felt compelled to disclose the correct number. This article first appeared on NBCNews.com. Read more from NBC News here: Biden stays on the sidelines as Congress scrambles over a looming shutdown UnitedHealthcare CEO murder suspect Luigi Mangione hit with federal charges in New York after waiving extradition Here’s what happens if the government shuts down right before the holidays