NATO Secretary-General Jens Stoltenberg on Tuesday pledged to continue backing Ukraine in its "grinding war of attrition" against Russia.

In the lead up to the Wednesday six-month anniversary of Russia’s invasion of Ukraine on Feb. 24, Stoltenberg participated virtually in a forum hosted by Ukraine along with dozens of other world leaders.

"Winter is coming and it will be hard," Stoltenberg told world leaders. "This is a battle of wills and a battle of logistics."

Stoltenberg NATO

NATO Secretary General Jens Stoltenberg pauses as he delivers a statement to the media prior to a meeting at the European Parliament in Brussels, April 28. (AP/Olivier Matthys)

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The NATO head said the alliance "must sustain" its support for Ukraine for "the long-term" in order to make sure Kyiv is able to successfully repel Russian forces from its borders.

But as world leaders vow to continue supporting Ukraine militarily and through humanitarian aid, Kyiv is making sure it has the international backing to restore all of Ukraine’s sovereignty – including in the Crimean Peninsula.

"It all began with Crimea, and it will end with Crimea," Ukrainian President Volodymyr Zelenskyy told world leaders, citing an imprisoned Ukrainian activist from Crimea. "It is necessary to liberate Crimea. This will be the resuscitation of world law and order."

Ukraine soldiers

DONBASS, UKRAINE - JUL 23: Ukrainian soldiers in a truck on the Donbass frontline Donetsk, (Ukraine), 23 July 2022. (Photo by Diego Herrera Carcedo/Anadolu Agency via Getty Images)

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Zelenskyy championed the support of nearly 60 nations and international organizations in Tuesday’s summit, including the attendance of some 40 presidents and prime ministers.

Though while the Ukrainian president applauded the support Kyiv has received since Russia’s February invasion, he suggested the failure to hold Moscow accountable for its 2014 invasion and subsequent occupation of Crimea is why Ukraine is at war today.

Zelenskyy argued the only way to ensure security across Europe was to prevent Russia’s military ambitions from succeeding in Ukraine. 

Russia has relied on its presence in Crimea as a launching pad for its invasion to not only provide logistical support in southern and eastern parts of the country, but for tactical aims as well.

Kherson troops

Dnipropetrovsk Oblast, UKRAINE - MAY 09: Ukrainian infantrymen train on May 09, 2022 near Dnipropetrovsk Oblast, Ukraine. Infantry soldiers learned scenarios to survive when potentially confronted with a Russian tank closing in at close range.  (Photo by John Moore/Getty Images)

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Zelenskyy said since the start of the war some 750 cruise missiles have been launched from the Crimean Peninsula at Ukrainian targets.

"We need to win the fight against Russian aggression, and therefore we need to free Crimea from occupation. It will end where it began," Zelenskyy said.