WASHINGTON>> President Joe Biden brushed off a threat from Russian leader Vladimir Putin about war against the West if Ukraine’s allies allow it to use weapons deeper inside Russia. It’s a shift that Kyiv has pleaded for, but no decision was immediately announced after a meeting Friday between Biden and Britain’s prime minister.

Ukraine and many of its supporters in the U.S. and Europe want Biden to lift restrictions on Western-provided long-range weapons, and there are signs Biden might shift the administration’s policy.

The U.S., concerned about any step that could lead Russia to escalate the conflict, has moved cautiously before granting a series of earlier requests from Ukraine for specific arms, including advanced tanks, missiles and rocket systems, and F-16 fighter jets. Russian officials have issued similar threats before many of those past decisions.

Ukraine was a key topic for Biden and British Prime Minister Keir Starmer after this week’s visit to Kyiv by their top diplomats, who came under fresh pressure to loosen weapons restrictions. So far, the U.S. has allowed Ukraine to use American-provided weapons only in a limited area inside Russia’s border with Ukraine.

Two U.S. officials familiar with discussions said they believed Starmer was seeking Biden’s approval to allow Ukraine to use British Storm Shadow missiles for expanded strikes in Russia. Biden’s approval may be needed because Storm Shadow components are made in the U.S. The officials, who spoke on condition of anonymity, said they believed Biden would be amenable.

Starmer said talks would continue when global leaders convene for the annual U.N. General Assembly gathering this month.

“This was a really important invitation from the president to have this level of discussion about those critical issues,” he told reporters after the White House meeting. He added, “Ukraine has a right to self-defense, and we’ve stood united.”

Putin said a day earlier that allowing long-range strikes “would mean that NATO countries, the United States and European countries, are at war with Russia.” His remarks were in line with the narrative the Kremlin has promoted since early in the war, accusing NATO countries of de-facto participation in the conflict and threatening a response.

Speaking to journalists before the private talks with Starmer, Biden said he wanted to make “clear that Putin will not prevail in this war.”

Asked what he thought about Putin’s threat, Biden answered, “I don’t think much about Vladimir Putin.”

Ukrainian President Volodymyr Zelenskyy has been pressing the U.S. and other allies to allow his forces to use Western weapons to target Russian air bases and launch sites far from the border as Russia has increased assaults on Ukraine’s electricity grid and utilities before winter.

“The war must become more difficult for Russia — that is the only way to make them realize it must end,” he posted Friday on social media.

Zelenskyy’s appeal has garnered support in U.S. and European security and diplomatic circles, including from some former U.S. generals and diplomats, lawmakers and security analysts. They argue that Russia’s previous threats of escalation against the West have proven hollow and that the U.S. restrictions on weapons are making it impossible for Ukraine to gain the battlefield momentum it needs.

Even a few Ukrainian strikes with heavier weapons on military targets deeper into Russia would put more strain on Russian logistics, troops and other resources, said George Barros, a security analyst for the Institute for the Study of War.