Under pointed questioning from senators, the top U.S. general for homeland defense said Tuesday that he sees no military threat coming from the southern border with Mexico, but his focus in on “very real” threats from China and Russia in the north.

Air Force Gen. Terrence O’Shaughnessy, commander, U.S. Northern Command and North American Aerospace Defense Command, told a Senate committee that proposed barriers along the U.S.-Mexico border could increase security against any potential military threats coming from the south. But he said Russia’s advancements in training and capabilities, and its intent to hold the U.S. at risk, present an urgent threat to America.