WASHINGTON — Kazakhstan has agreed to let the United States fly troops and weapons over its territory, a deal that opens a direct and faster route over the North Pole for American forces and lethal equipment headed to Afghanistan.

Right now, troops and lethal material typically travel from the United States to Ramstein Air Base in Germany and then fly south along the Arabian Gulf and up to Afghanistan via Pakistan — avoiding a more direct route over Iran, because Iran does not allow American military overflights. The new route over the North Pole to Bagram Air Base, the military’s main air hub in Afghanistan, will allow troops to fly direct from the United States in a little more than 12 hours.

The agreement was reached at a meeting Sunday in Washington between President Obama and President Nursultan Nazarbayev of Kazakhstan, who is in Washington for a 47-nation summit meeting on nuclear security.. Officials said that the formal deal is not yet complete, but that the agreement of the Kazakh president to the overflights, which American military officials had long sought, was an important development in the Afghanistan war effort.

“The devil is the details, but this is obviously a great positive moment,” said Capt. Kevin Aandahl, a spokesman for the United States Transportation Command, which oversees military transport logistics.

Michael McFaul, the senior director for Russia on the National Security Council staff, told reporters in a conference call on Sunday that the deal would make transportation challenges less difficult for American commanders.

“This will save money; it will save time in terms of moving our troops and supplies into the theater,” he said.

Lethal supplies include not only weapons but also armored trucks designed to protect American forces from roadside bombs. Most non-lethal supplies to Afghanistan go over land or by sea.