Biden and Starmer Aim to Help Ukraine Without Triggering a Wider Conflict

President Biden’s deliberations with British Prime Minister Keir Starmer about whether to allow Ukraine to attack Russia with long-range Western weapons were fresh evidence that the president remains deeply fearful of triggering a dangerous, wider conflict.

But the decision now facing Mr. Biden after Friday’s closed-door meeting at the White House — whether to sign off on the use of long-range missiles made by Britain and France — could be far more consequential than previous concessions by the president that delivered largely defensive weapons to Ukraine during the past two-and-a-half years.

In remarks at the start of his meeting with Mr. Starmer, the president underscored his support for helping Ukraine defend itself but did not provide an answer about whether he is willing to do more to allow for long-range strikes deep into Russia.

“We’re going to discuss that now,” the president told reporters.

For his part, the prime minister noted that “the next few weeks and months could be crucial — very, very important that we support Ukraine in this vital war of freedom.”

European officials said earlier in the week that Mr. Biden appeared ready to approve the use of British and French long-range missiles, a move that Mr. Starmer and officials in France have said they want to provide a united front in the conflict with Russia. But Mr. Biden has hesitated to allow Ukraine to use arms provided by the United States in the same way over fears that President Vladimir V. Putin of Russia would see it as a major escalation.

On Thursday, Mr. Putin responded to reports that America and its allies were considering such a move by declaring that it would “mean that NATO countries — the United States and European countries — are at war with