Poland’s Fraught Offer: Fighter Jets for Ukraine, but Only Through U.S. Hands

President Biden’s commitment to keeping the United States from engaging in direct combat with Russian forces faced an unexpected test this week, when Poland surprised American officials by offering to turn over its collection of aging, Russian-made MIG fighters, for ultimate transfer to Ukraine.

But the offer came with a hitch: Poland refused to give the MIGs directly to Ukraine. The deal would only go forward if the United States, and NATO, did the transferring, and then replaced Poland’s fleet with American-made fighter jets. The United States, blindsided by the demand, began to pick apart what was going on. Polish leaders, fearful of incurring Russia’s wrath, and perhaps an attack on the air base where the MIGs launched from, was handing the problem of becoming a “co-combatant” in the war off to Washington and its other NATO allies.

The Pentagon all but rejected the idea on Tuesday night and said the United States had not been consulted. By late Wednesday, Defense Secretary Lloyd J. Austin III had put a stake through the whole idea, telling his Polish counterpart in a phone call that the proposed MIG transfer was a dead letter, Pentagon officials said.

“The transfer of combat aircraft could be mistaken for an escalatory step,” John F. Kirby, a Pentagon spokesman, told reporters.

In the midst of a remarkably unified alliance, the back and forth was a reminder that the joint effort to punish and ultimately repel Russia has a third rail that no one wants to touch. Ukraine’s allies will provide 17,000 anti-tank weapons in six days; they will train their cyberweapons on Russian targets. But they will not risk a dogfight over the skies of Ukraine, which, in the minds of many, is bound to bring them fully into the war.

That distinction was driven home on Wednesday, when Secretary of State Antony J. Blinken, who had initially seemed somewhat open to the idea of Poland giving its planes to Ukraine, said the idea of flying MIG-29 fighter jets to a U.S. air base in Germany for transfer to Ukraine lacked a clear “substantive rationale.”

“The prospect of fighter jets at the disposal of the United States Government departing from a U.S. NATO base in Germany to fly into airspace contested with Russia over Ukraine raises some serious concerns for the entire NATO alliance,” Mr. Blinken said during a news conference in Washington.

Then he got to his central point: “Our goal is to end the war, not to expand it — including potentially expand it to NATO territory,” Mr. Blinken said.

Administration officials, when promised anonymity, conceded that the political pressure on them to strike a deal to put Ukrainian pilots in cockpits was huge. While Russia’s air force has performed poorly so far, Ukraine’s ability to contest the skies with its current fleet is limited — and probably diminishing, once Russia moves in its sophisticated air defenses.

So when the United States rejected the proposal, Republicans leapt — the first time there has been a partisan breach on strategy.

“President Biden should explain exactly why he vetoed fighter jets for Ukraine,” Senator Ben Sasse, Republican of Nebraska and a member of the Senate Intelligence Committee, said in a statement.

He argued that the administration was giving Ukraine “Javelins and Stingers from NATO territory,’’ a reference to antitank and antiaircraft weapons. “So why exactly does President Biden think that Ukrainian MIGs, flown by Ukrainian pilots, would be shot down over NATO territory while they’re on their way to defend Ukrainian airspace?”

There were similar blasts from other Republicans.

In fact, the line between sending ammunition and sending weapons is a murky one. And while there may be legal distinctions, administration officials made clear that they had no doubt that President Vladimir V. Putin of Russia would regard sending the planes as an escalatory move.

American officials also believe that the jets, given Russia’s increasing anti-air capabilities in Ukraine, would have limited value to Ukraine and that they are not worth the risks they could pose to more effective means of bolstering the Ukrainian military. The move could, for example, prompt Russia to intensify its efforts to stop supply convoys carrying arms from allied countries.

The issue started about 10 days ago when Josep Borrell Fontelles, the European Union’s top foreign policy and security official, said at a news conference that the E.U. nations were going to provide “fighting jets. We’re not talking about just ammunition. We are providing more important arms to go to a war.”

He later backtracked, saying countries would individually decide what to do. The idea picked up traction in Congress. Many looked to Poland, as one of three nations that could provide the MIG fighters — which, by definition, are three decades old and hardly up to modern standards. (The Ukrainians want these planes because they know how to fly them — old MIGs, left over from Soviet days, make up their air force.)

But then Poland began to think about the Russian threats to attack any country that allowed Ukrainian jets to lift off from their airfields to engage Russian forces.

So Poland said it wanted to hand the planes over to the U.S. base at Ramstein, Germany, turning it into something of a used-plane lot for Cold War aircraft. It was up to the Americans, they said, to fix them up and give them to Ukraine.

Daniel Fried, a former senior State Department official and former U.S. ambassador to Poland, said the snafu seemed to have started with a miscommunication and snowballed from there.

“It feels like a mess. I suspect there is a chain of miscommunication that resulted in mixed signals to the Poles.”

“Borrell started it,” he said. “Then the U.S. failed to be clear with Poles and inadvertently gave mixed signals,’’ a reference to Mr. Blinken’s initial, seeming openness to the idea.

Mr. Fried concluded: “The administration needs not to explain why the MIGs are a bad idea. They need to explain what they will do to help the Ukrainians achieve what they wanted to achieve with the MIGs.”

Michael Crowley and Julian Barnes contributed reporting from Washington.