GEOFF BENNETT: Today, the leaders of Ukraine's two most important allies are meeting in Washington.

President Biden and British Prime Minister Keir Starmer have many topics on their agenda, but there is particular attention coordinating support for Ukraine and allowing Kyiv to use American and British long-range missiles to hit targets deep inside Russia.

Nick Schifrin is here following that story.

So, Nick, how are the U.S. and the U.K. trying to coordinate their overall strategy for Ukraine?

NICK SCHIFRIN: Geoff, Ukraine and its partners have a strategic goal, to try and convince Russian President Vladimir Putin that Ukraine and its soldiers can outlast Putin, can outlast Russia, and with the help of Western weapons inflict massive casualties on Russia's military on the battlefield.

And today, in the White House, President Biden said the U.S. and the U.K. were -- quote -- "working together to ensure Putin doesn't win."

To do that, U.S. and British officials tell me that they're discussing a few topics, one, guaranteeing Ukraine's long-term funding, including with Russian sovereign assets, building up Ukraine's and Europe's defense industrial base to complement the American defense industrial base, international coordination, including Ukraine's entry into the E.U.

and -- quote -- "irreversible path" toward NATO, and, of course, Geoff, battlefield successes.

That, Ukraine hopes, will be enabled with the ability to use long-range Western weapons to fire deep into Russia.

GEOFF BENNETT: So, what did they say about those long-range weapons?

NICK SCHIFRIN: Absolutely nothing publicly.

Senior U.S. officials insist that President Biden still has not made any decision whether to lift restrictions on Ukraine's use of ATACMS, which have a range of 190 miles to be able to be fired deep into Russia.

There's a debate.

But some senior U.S. officials continue to argue the targets that Ukraine wants to hit are beyond that range, the relatively few ATACMS that Ukraine has are better used in occupied Crimea, and ongoing concerns that a U.S. official tells me about tonight about what Russia might do in response if that policy has changed.

Now, the British government does allow its purely British weapons to be fired anywhere that Ukraine wants, but it has not allowed its longest-range weapon, that is the Storm Shadow, to be fired by Ukraine deep into Russia, because the Storm Shadow has American parts and relies on American GPS and American mapping.

So a Western official tells me tonight the British government wants the U.S. to be -- quote -- "comfortable" with the use of Storm Shadows to be fired deep into Russia.

That is what the prime minister and the president are talking about, the logistics of that, but also a political understanding of whether Britain can, in fact, give Ukraine that authorization.

If there's an agreement, Geoff, though, do not expect it to be announced publicly.

A Western official tells me -- quote -- "The first announcement of this policy will land when the first missile lands in Russia."

Now, as for that U.S. concern about escalation, well, Putin threatened exactly that in comments yesterday.

VLADIMIR PUTIN, Russian President (through translator): If this decision is made, it will mean nothing less than the direct participation of NATO countries, the United States and European countries in the war in Ukraine.

This, of course, significantly changes the very essence, the very nature of the conflict.

We will make appropriate decisions based on the threats that will be created for us.

NICK SCHIFRIN: One last U.S. and U.K. concern, Geoff, is that both countries produce fewer long-range weapons in terms of the actual numbers that they can produce, far fewer than Ukraine wants or needs on the battlefield.

Ukraine argues, look, give us whatever you can.

Putin's threat is empty.

There are targets that are within the range of these weapons, and the use of the weapons fit into that larger strategy that you and I talked about.

GEOFF BENNETT: Nick Schifrin thanks, as always.

NICK SCHIFRIN: Thank you.