President Volodymyr Zelensky, days after winning promises of battle tanks, is exhorting his Western backers to send more heavy weapons to Ukraine — and fast, to help stave off a new Russian offensive.
Having persuaded the United States and Germany to send dozens of their best tanks, Ukrainian officials have also started to press Western officials on advanced weapons like long-range missiles and fighter jets.
“Russia hopes to drag out the war, to exhaust our forces,” Mr. Zelensky said in his nightly address on Sunday. “So we have to make time our weapon. We must speed up the events, speed up the supply and opening of new necessary weaponry options for Ukraine.”
On Monday, President Biden, asked by a reporter whether the United States would provide F-16 fighter jets — which are on Ukraine’s wish list — said it would not. The White House declined to comment on a question about whether Mr. Biden was ruling out the use of the jets entirely or just an immediate transfer of them.
But even when it comes to the weapons Ukraine has succeeded in securing, the country faces an urgent problem of logistics: How fast can the new tanks arrive? And will they be in time to help repel an expected Russian offensive that could begin as soon as February?
Already Russia has shown signs of newly aggressive action on the battlefield, making small gains around the city of Bakhmut in eastern Ukraine. By drafting hundreds of thousands of men last fall, Russia has shored up its battered positions and reinvigorated its ranks. Now it is trying to wear down Ukrainian defenses with waves of soldiers.
“They are simply throwing bodies at our positions and numbers and gradually moving forward,” Serhiy Haidai, the head of the Luhansk regional military administration, said on national television Sunday night.
Both Ukraine and Russia have used the winter to train their soldiers, rebuild units and prepare for spring offensives. The extraordinary sanctions the West has imposed on Russia, despite eroding its economy, do not appear to have affected the determination of President Vladimir V. Putin to pursue his invasion.
In recent weeks, the United States, Germany and Britain have announced an array of new weapons for Ukraine, hoping to bolster its defenses as the war enters a second year.
On Monday, NATO’s secretary-general, Jens Stoltenberg, tried to broaden the coalition by urging South Korea to increase its support for Ukraine, hinting that Seoul should consider sending military aid, a move it has so far resisted. South Korea is not a member of the alliance but has close ties to it.
“I will say that several NATO allies, who had as a policy never to export weapons to countries in conflict, have changed that policy now,” Mr. Stoltenberg said.
But even those promised weapons will not be in place right away.
The first set of tanks likely to arrive, Challenger 2s pledged by the British government early this month, will not make it to Ukraine until late spring, Britain’s defense secretary said on Monday.
“What I can say is that it will be this side of the summer: May, or probably toward Easter time,” the defense secretary, Ben Wallace, told lawmakers in Parliament. He declined to give specifics about timing “for security reasons,” but said that the 14 tanks, enough to form one company, would reach Ukraine after a period of training.
Germany and the United States, too, have outlined only a vague timeline of months for tanks to reach Ukraine.
Germany’s defense minister, Boris Pistorius, has said it could take about three months for 14 of the country’s Leopard 2 tanks to be operational in Ukraine. And a Pentagon spokeswoman, Sabrina Singh, told reporters last week that it would take “months” for the United States to get 31 M1 Abrams tanks there.
A top adviser to Mr. Zelensky, Andriy Yermak, suggested on Monday that Ukraine was also pressing NATO countries on the question of warplanes, saying on Telegram that Kyiv had received “positive signals” from Poland about F-16 fighter jets. Poland, an early advocate of sending German-made tanks to Ukraine, has stressed that it coordinates weapons decisions with other NATO members.
And Chancellor Olaf Scholz of Germany reiterated in recent days that Berlin would not send fighter jets to Ukraine. “That we are not talking about fighter aircraft is something I made clear very early on, and I’m making that clear here as well,” he said.
Wopke Hoekstra, the foreign minister of another NATO member, the Netherlands, recently told Dutch lawmakers that the government would be willing to supply Ukraine with F-16 jets if Kyiv requested them and the United States authorized the transfer. “We are open-minded,” he said. “There are no taboos.”
Until Mr. Biden, speaking on the South Lawn of the White House on Monday, appeared to rule out sending the fighter jets, at least for now, U.S. officials had seemed noncommittal on the question. Last March, when Poland was exploring ways to send some of its Soviet-era fighter jets to Ukraine, the deal was scuttled after American officials balked, amid concern that sending planes could lead to an expansion of the war.
On Monday, the Kremlin’s spokesman, Dmitry Peskov, warned of just that, saying that further supplies of weaponry to Ukraine would lead to a “significant escalation” of the conflict.
Ukrainian officials argue that jets would significantly help their defenses, and improve their ability to fend off the Russian aircraft that have been firing into Ukraine. But the proliferation of surface-to-air missiles on both sides has ensured that air combat and bombing runs are relatively rare.
Michael Kofman, director of Russian studies at C.N.A., a research institute in Arlington, Va., said that jets “would reduce Ukraine’s disadvantage versus the Russian Air Force, and simplify the use of Western air-launched munitions, but this is a lower priority issue all things considered.”
The United States’ supply of anti-radar missiles that began over the summer allowed Ukraine’s air force — primarily composed of Soviet-era jets and helicopters — to fire ordnance far enough away from the front lines to skirt Russian air defenses. But almost one year into the war, Ukraine’s aerial fleet is overused and in need of repair, much like the tanks and armored vehicles in the country’s ground forces.
Germany’s decision to send its Leopard tanks has paved the way for other European nations to ship their own to Ukraine. The speed at which they do so will be determined by each government, based largely on how many Leopards are immediately available and whether they will need to be refurbished and reprogrammed for the current fight.
But it remains far from clear whether the dozens of tanks, even if they arrive relatively quickly, will be enough to either repel a Russian offensive or help Ukraine retake significant ground. Although Ukrainian forces have clung to Bakhmut for months, for instance, the area may finally slip into Russian control before the tanks can make it to the fight.
Part of the problem is not delivery but training.
Most of the Ukrainian troops selected to crew the Western tanks will most likely already have been trained on Soviet-era tanks, so learning to use the Leopards might take only three to four weeks “to achieve a basic proficiency,” the International Institute for Strategic Studies said this month. German officials have reportedly estimated that it will take about six weeks.
But learning to use the American-made Abrams — a highly sophisticated war machine — is expected to take longer, according to U.S. officials. Ms. Singh, the Pentagon spokeswoman, said teaching soldiers how to operate and maintain them “is going to take a very long time.”
Beyond that, Ukrainian officials have said they need about 300 tanks — a number that Western nations, leery of dipping too deeply into their inventories, may not be willing to provide.
Ms. Singh alluded to stockpile concerns last week, saying, “We just don’t have these tanks available in excess in our U.S. stocks.” Some military experts have estimated it could take a year or even longer for the Abrams tanks to arrive at the battle.
Sonny Butterworth, a land warfare expert and senior analyst at Janes, the London-based defense intelligence firm, said NATO states that are going to train Ukrainian troops on Western tanks would most likely “give them the basics.” Training for longer-term maintenance, sustainability and other care for the tanks will probably come later, he said.
“That might be something they have decided to cut out — it seems they are trying to get the Ukrainians as much as quickly as possible,” Mr. Butterworth said.
“Speed is of the essence,” he said.
Reporting was contributed by Zolan Kanno-Youngs, Ivan Nechepurenko, Marc Santora, Cassandra Vinograd, Carly Olson and Matthew Mpoke Bigg.
