Northern Syria — Inside Syria, U.S. forces brought out the big guns Monday, including Bradley Fighting Vehicles at a remote base, significantly ramping up U.S. firepower. Major General Eric Hill said their arrival is to counter new threats on the battlefield.

"We've been conducting a withdrawal. We've been resetting ourselves here in the east and as we do that, we want to make sure we have the right mix of different vehicles and combat power here to sustain ourselves," Hill said.

That power is not to match ISIS, but the militaries of the Syrian regime, the Russians, or even militias backed by fellow NATO partner Turkey. All are now carving up territory once controlled by America and its Kurdish allies.

"Force protection is always something that U.S. forces will ensure," Hill said.

But U.S. forces protecting oil fields face renewed threats after Russian Foreign Minister Sergei Lavrov insisted that Syrian forces must soon take them back under their control.

On Monday, there was a reminder of the constant terror threat in Syria. A car bomb in the northern city of Qamishli, followed by another, caught on someone's cell phone. No one has yet claimed responsibility. The carnage adding to the chaos of a relatively peaceful region of this country that now grows more volatile by the day.