Today, Moscow demanded that it must participate in any security guarantees provided by the U.S. and Europe to Ukraine.

That is likely a nonstarter for the West that illustrates the challenge facing the allies as they try to forge a path toward peace.

AMNA NAWAZ: Russia's new demand comes as the chairman of the Joint Chiefs of Staff met today with his European colleagues here in Washington and NATO's military chiefs met in Europe, hoping to create a plan that would provide Ukraine the ability to defend itself and ensure its future security should the two sides come to a peace agreement.

Nick Schifrin begins our coverage of today's military meetings as Russia continues to wage its war on Ukraine.

NICK SCHIFRIN: In Northeast Ukraine today, on day 1,273 of this full-scale war, life looks like hell.

And for the residents of Sumy today who escaped their homes hit by a Russian drone, peace feels impossibly distant.

This is the kind of attack that 32 NATO military chiefs met today to try and help Ukraine prevent.

They plan security guarantees to protect a postwar Ukraine, as did Chairman of the Joint Chiefs Dan Caine, whom European officials tell "PBS News Hour" met his European counterparts today in the Pentagon.

France and Britain are willing to deploy thousands of troops into Ukraine to help observe any peace deal.

They would also help support and train Ukrainian troops, Europe's most capable military, often fighting with Western weapons that need maintenance.

But they can't do it alone.

European forces need American intelligence, coordination, logistics and weapons.

Ukraine wants $90 billion worth of American weapons paid by Europe, both offensive and defensive, including Patriot air defense.

The U.S. publicly hasn't revealed how much military support it will provide, but it will include assistance from the air, President Trump said yesterday in a FOX News phone call.

DONALD TRUMP, President of the United States: When it comes to security, they're willing to put people on the ground.

We're willing to help them with things, especially probably if you talk about by air.

We will give them very good protection, very good security.

NICK SCHIFRIN: What's new this week is President Trump's assurances on Monday to Ukrainian President Volodymyr Zelenskyy and to European leaders the U.S. will help.

That's enough direction for the military planners to begin to detail how the U.S. can help backstop a European force.

And European officials say U.S. help is necessary.

EMMANUEL MACRON, French President: And this coalition will work very actively now with the United States of America, which is a great news.

NICK SCHIFRIN: But Foreign Minister Sergey Lavrov today demanded Russia have a say in those security guarantees, suggesting Moscow would demand the ability to reject them.

SERGEY LAVROV, Russian Foreign Minister (through translator): We cannot seem to agree that issues of security and collective security are now being proposed without the Russian Federation.

It won't work.

NICK SCHIFRIN: Which shows enormous gaps between the two sides as Russia continues to wage its war.

For the "PBS News Hour," I'm Nick Schifrin.