NATO's chief Mark Rutte told Ukrainian President Volodymyr Zelensky on Thursday that his goal as head of the Western military alliance was to ensure that "Ukraine prevails."
In a major show of support for Kyiv, Rutte went to the Ukrainian capital for his maiden trip as secretary general of the alliance.
But in a joint media appearance, Zelensky blasted Western delays over supplying long-range weapons he says are critical to fighting off the Russian invasion, and called on NATO members to shoot down Russian missiles and drones fired on Ukraine.
Meanwhile, Russia confirmed it had captured the eastern town of Vugledar, underscoring the difficulties Ukrainian troops face across the sprawling 1,000-kilometre (620-mile) front line.
Kyiv relies on billions of dollars in Western military aid to fight the Russian invasion, with the NATO leader a powerful voice corralling support for Ukraine on the global stage.
Rutte said he chose Kyiv as his first trip "to make crystal clear to you, to the people of Ukraine and to everyone watching, that NATO stands with Ukraine."
"It is my priority and my privilege to take this support forward...working with you to ensure that Ukraine prevails."
Zelensky has said that without Western aid, Ukraine has no chance of winning the war.
But he has also chided delays in shipments and criticised restrictions that he says limit Kyiv's ability to hit back -- statements he repeated alongside Rutte on Thursday.
"We need sufficient quantity and quality of weapons, including long-range weapons, that, in my opinion, our partners are already dragging out," Zelensky said.
The Ukrainian leader also called on NATO members to take a more active role in helping his country to fend off Russian aerial attacks.
"We will continue to convince our partners of the need to shoot down Russian missiles and drones," Zelensky said.
"We realise that this is a difficult decision ... they are not ready yet."
The former Dutch prime minister assumed NATO's top job on Tuesday at a pivotal moment, with Russia advancing on the battlefield, China flexing its growing might, and just weeks before US voters choose a new leader.
The Dutch government was one of Kyiv's most important European backers, a driving force pushing for delivering advanced F-16 fighter jets to Kyiv.
He was also prime minister when Malaysia Airlines flight MH17 was shot down over Ukraine in 2014, killing 298 people, the majority of them Dutch.
He said the crash "changed my personal view of the world" and made him all the more determined to support Ukraine, "for their security and ours."
Alongside calls to shoot down Russian missiles and drones, Ukraine is also pushing the United States to allow Western-supplied missiles to be used to strike military targets inside Russia.
Cautious to avoid a possible escalation, Washington has been hesitant to give the green light.
Ukraine faces a critical few months, possibly its most difficult winter, on the battlefield.
Russian forces have been advancing through the east for most of 2024 and are targeting the key logistics hub of Pokrovsk.
With Moscow's troops less than 10 kilometres (six miles) away, its fall would severely hamper Ukrainian supply routes and defensive positions in the Donetsk region.
On Thursday the defence ministry in Moscow said its forces had captured the town of Vugledar, marking Russia's most significant territorial gain for weeks.
Ukraine's army had said a day earlier they were withdrawing from the town, which was home to 14,000 people before Russia invaded but has been ravaged by more than two and a half years of fighting.
Ukraine also said Russian drone attacks on a border settlement in its northern Chernigiv region killed three, including a young child.
Russian strikes have battered Ukraine's energy grid and destroyed much generating capacity. Ukraine is braced for blackouts that could plunge millions into darkness, cutting off heating and hot water in sub-zero temperatures.
Meanwhile the possible return of aid-sceptic Donald Trump to the White House has raised questions about how long Ukraine's most important backer will carry backing its fight against Moscow.
