WASHINGTON D.C. (WVEC) -- U.S. troops have been fighting in Afghanistan since 2001.

U.S. Central Command Commanding General Joseph Votel told senators Tuesday part of the new U.S. strategy is to go after a multi-billion dollar drug trade. The Taliban has relied on the drug trade for years to fund its operations.

"This is a lesson learned from Iraq and Syria when we got serious about going after the funding streams supporting ISIS, we started seeing an immediate impact, so that is exactly the intention here," he said. "With ISIS largely defeated in Iraq and Syria, the United States is shifting more assets to the war effort in Afghanistan."

"Our efforts are not only targeting their production and storage locations but also working with regional people to help limit the flow of that product out f the region," he said. "Again, trying to impede their ability to benefit from that."

Things got a little testy when Votel was unable to answer South Carolina Lindsey Graham's question about U.S. objectives in Syria.

"Is it still our policy that Assad must go?" asked Graham.

Votel responded: "I don't know that that's our particular policy at this particular point,"

Graham replied: "Well if you don't know, I doubt anybody does know because this is your job to take care of that part of the world?"

About Syria, and the U.S. strategy there, Virginia's Tim Kaine weighed in, saying: "We're really puzzled by it."

General Votel replied that fighting alone can't resolve the issues in Syria and that what's needed, he said, is, "talking through diplomatic means, under the U.N."