World marks one year since Russia invaded Ukraine

STORY: In Paris, the Eiffel tower blazed blue and gold.

At the United Nations, a resolution demanding Russia withdraw its troops.

And at this training camp for Ukrainian soldiers in Britain , the one-year anniversary of Russia invading Ukraine was marked by a moment of silence.

Calls for peace and tributes to the fallen took place in cities around the world Thursday, while Ukraine’s First Lady Olena Zelenska called attention not to the war's atrocities, but to Ukraine's remarkable resilience since last February 24th.

ZELENSKA: "today we are not commemorating a year of war, but we are celebrating a year of resistance to aggression, a year of courage, a year of mutual assistance and rescue of each other, a year of humanity, and a year of friendship."

The war has rallied Western allies into a unified defense of Ukraine, providing billions of dollars in weapons since Russia invaded.

NATO Secretary-General Jens Stoltenberg on Thursday told Reuters the invasion was part of a pattern that included Russian military action in Georgia in 2008 and Donbas and Crimea in Ukraine in 2014.

"We don't know when the war will end. But what we do know is that when the war ends, we need to ensure that history doesn't repeat itself. // And therefore we need to ensure that Ukraine has the military capabilities, the strength, to deter further aggression and also find frameworks to ensure that Russia doesn't attack again."

But on the battlefield, intense fighting rages on.

Near Bakhmut - now Russia's main target - constant explosions could be heard echoing in the distance as Ukrainian soldiers held their ground.

Western officials said Russia had planned an offensive to capture new territory ahead of the anniversary to give President Vladimir Putin a victory to announce.

Moscow's forces have made progress trying to encircle Bakhmut, but have taken heavy losses.

Meanwhile Putin announced plans on Thursday to boost Russia's nuclear arsenal, after suspending its participation in the START nuclear arms treaty this week.

PUTIN: "We will continue to inundate our forces with advanced technology. There are new strike systems, intelligence gathering and communications equipment, drones and artillery systems."

Russia still holds nearly a fifth of Ukraine, despite losing territory in major battlefield setbacks in what it calls its "special military operation."

Tens of thousands of Ukrainian civilians and troops on both sides are believed to have died in the war. Russian forces have destroyed Ukrainian cities and set millions of refugees to flight.