President Joe Biden appears on the verge of clearing the way for Ukraine to launch long-range Western weapons deep inside Russian territory, as long as it doesn’t use arms provided by the United States, European officials say.

The issue, which has long been debated in the White House, is coming to a head Friday with the first visit to Washington by Britain’s new prime minister, Keir Starmer.

Britain has already signaled to the United States that it is eager to let Ukraine use its “Storm Shadow” long-range missiles to strike at Russian military targets far from the Ukrainian border. But it wants explicit permission from Biden in order to demonstrate a coordinated strategy with the United States and France, which makes a similar missile. U.S. officials say Biden has not made a decision, but will hear from Starmer on Friday.

If the president approves, the move could help Ukraine hold the line after it seizes Russian territory, as it did during its surprise incursion into Russia’s Kursk region. But Biden has hesitated to allow Ukraine to use U.S. weapons in the same way, particularly after warnings from U.S. intelligence agencies that Russia could respond by aiding Iran in targeting U.S. forces in the Middle East.

On Thursday, White House officials insisted there was no imminent decision on the use of the American-made surface-to-surface Army Tactical Missile Systems — known as ATACMS. But Biden himself has signaled that a loosening of restrictions is coming. He was asked Tuesday whether he was ready to grant the increasingly insistent requests from President Volodymyr Zelenskyy of Ukraine.

“We are working that out right now,” he said.

If Biden permits the British and French to go ahead, and if he follows in coming weeks by allowing the use of the ATACMS, it could well be his final acceleration of the military aid to Ukraine.

Quietly, Republican leaders in the Senate, especially Sen. Mitch McConnell, the minority leader, have been urging an aggressive response — a sharp split with former President Donald Trump, who refused in Tuesday night’s presidential debate to declare that he wants Ukraine to win, or to say that Russia should get out of the 20% or so of Ukraine it has taken since war began.

Putin warning

On Thursday, President Vladimir Putin of Russia issued an unusually specific warning to the West, noting that the Ukrainians alone cannot operate the long-range missiles, because they require Western technical help and satellite guidance.

“This will mean that NATO countries — the United States and European countries — are at war with Russia,” Putin said, according to a report by the Kremlin. “And if this is the case, then, bearing in mind the change in the essence of the conflict, we will make appropriate decisions in response to the threats that will be posed to us.”

For the United States, assessing how much to believe Putin has been a difficult task. Over nearly 31 months of war, the pattern has been clear: At every stage, Biden has been concerned that providing new weapons to Ukraine, or allowing Ukraine’s military to shoot into Russian territory, would cross one of Putin’s red lines.

In the opening months of the war, Biden was reluctant to provide HIMARS artillery to Ukraine, then M1 Abrams tanks, F-16 fighter jets and short- and then longer-range ATACMS. But in each case, as the administration discovered Putin appeared less eager to escalate the war than initially believed, it loosened the reins.

In the spring, for the first time, Biden approved allowing Ukraine to fire at Russian artillery and other targets just over the Russian border, to avoid giving Putin’s forces a haven for attacking cities and towns around Kharkiv. That permission was later expanded. But striking the border areas is essentially a defensive operation. Senior White House officials say there remains worry about using American ATACMS to strike more than 60 or so miles into Russia.

In classified briefings, U.S. intelligence officials have expressed deeper concerns about direct, visible American participation in Ukraine’s move to seize and hold positions near Kursk. There are indications, they have warned, that Russia could provide technological help that would allow Iran and its proxy forces to attack U.S. forces in the Middle East. The administration this week accused Iran of shipping missiles for the first time to Russia for use in the war, an accusation the government in Iran has denied.

In a series of meetings with senior administration officials in recent weeks, Ukrainian officials have been arguing that their seizure of actual territory inside Russia demonstrates that U.S. fears of crossing Russian red lines were overblown. The United States, those Ukrainian officials argue, should allow Ukraine to use U.S. weapons to strike deeper into Russia.