"This is critical, and there is an urgency to getting this program going," Nicholson said, but "it will take -- from the time funding is approved until the aircraft's arrival on the battlefield -- over 20 months."
A buy-American uproar in Congress, coupled with concerns over Russian aggression in Syria and Ukraine, forced the Pentagon to scrap the initial plan to keep buying Mi-17s for Afghanistan's Air Force from the Kremlin-run Rosoboronexport arms agency.
Nicholson, commander of U.S. Forces-Afghanistan and NATO's Resolute Support mission, told the Senate Armed Services Committee that the plan is to include funding for upgraded Black Hawks to deal with Afghanistan's high-altitude terrain in a supplemental budget request being drawn up in the House.
"I'm told this will be a part of the next supplemental submission that will be made," Nicholson said. The plan will also depend upon continuation of the Special Immigrant Visa program to allow Afghan pilots and ground crews to come to the U.S. for training.
"So we want to get these aircraft and these crews into the fight as soon as possible," he said.
Earlier in his committee testimony, Nicholson said the Afghan war is at a "stalemate" and the Black Hawks are necessary "to break the stalemate."
In addition, "the use of U.S. airframes, U.S. training, deepens the relationship with the Afghans and the U.S. and, of course, much of that funding goes back into the U.S. economy," he said.
"Offensive capability is what will break the stalemate in Afghanistan," Nicholson said. "The key offensive capabilities for the Afghan security forces are their special forces and their Air Force."
The Afghans have been relying on the Mi-17s mainly for troop transport, heavy lift and medevacs, but their reliability has been impacted by Russia's refusal to continue supplying spare parts after the U.S. canceled the contract to buy more helicopters.
Afghanistan has about 46 Mi-17s, but the U.S. Special Inspector General for Afghan Reconstruction (SIGAR) recently reported that the Mi-17s are "in a state of steady decline due to higher-than-anticipated utilization rates and accelerating attrition."
Earlier this week, House Armed Services Committee Chairman Rep. Mac Thornberry, a Texas Republican, said he is working with the administration of President Donald Trump on an $18 billion supplemental budget request.
"The administration has been very clear and consistent that they will send up a supplemental request for 2017 in the coming days. The sooner the better," Thornberry said.
Last year, the administration of former President Barack Obama requested $264 million for Black Hawks to replace the Mi-17s, but the request was not included in the National Defense Authorization Act.
During the long transition to the Black Hawks, the Afghans and Nicholson will be left with the difficult maintenance problem for the existing Mi-17 fleet.
At a December briefing at the Pentagon, Nicholson said the Afghan government had gone to the Russians to ask for help with spare parts and maintenance, but the request was rejected.
"The Afghan government solicited from them help with maintaining these airframes, but the Russians have not agreed to do it," Nicholson said. The result is that "the maintenance of this fleet is going to be very difficult."