The top U.S. military adviser to President Biden inspected the weapons transfer operation in an unannounced trip, meeting with troops and personnel from 22 countries who were working around the clock to unload the armaments for transport by land to the Ukrainian forces.

The American weaponry, which included the Javelins as well as small arms and munitions, was part of a $350 million package that Mr. Biden authorized on Saturday; within two days, one official said, the deliveries were landing at an airfield near the border that can process 17 airplanes a day. What began as a trickle — with only two or three planes arriving a day — is now a steady flow, the official said, with 14 loads from one airfield alone.

Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, included a stop at the airfield as part of a trip to the region. As he spoke to troops, cargos of Javelins rolled behind him. Nearby, two C-17s, the enormous cargo workhorses of the U.S. Air Force, sat on the tarmac.