NATO countries haven’t delivered what they promised to Ukraine in time, the alliance’s chief said Monday, allowing Russia to press its advantage while Kyiv’s depleted forces wait for military supplies to arrive from the U.S. and Europe.

“Serious delays in support have meant serious consequences on the battlefield” for Ukraine, NATO Secretary-General Jens Stoltenberg told a news conference in Kyiv with Ukrainian President Volodymyr Zelenskyy.

Outgunned, Ukraine’s troops have struggled to fend off Russian advances on the battlefield. They were recently compelled to make a tactical retreat from three villages in the east, where the Kremlin’s forces have been making incremental gains, Ukraine’s army chief said Sunday. The Russian Defence Ministry claimed Monday its forces had also taken the village of Semenivka.

“The lack of ammunition has allowed the Russians to push forward along the front line. Lack of air defence has made it possible for more Russian missiles to hit their targets, and the lack of deep strike capabilities has made it possible for the Russians to concentrate more forces,” Stoltenberg said.

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Kyiv’s Western partners have repeatedly vowed to stand with Ukraine “for as long as it takes.” But vital U.S. military help was held up for six months by political differences in Washington, and Europe’s military hardware production has not been able to keep up with demand. Ukraine’s own manufacturing of heavy weapons is only now starting to gain traction.

Now, Ukraine and its Western partners are racing to deploy critical new military aid that can help check the slow and costly but steady Russian advance across eastern areas, as well as thwart drone and missile attacks.

Zelenskyy said new Western supplies have started arriving, but slowly.

“This process must be speeded up,” he said at the news conference with Stoltenberg.

Though the 1,000-kilometre front line has shifted little since early in the war, the Kremlin’s forces have in recent weeks edged forward, especially in the Donetsk region, by sheer weight of numbers and massive firepower used to bludgeon defensive positions.

At least 4 dead in Odesa strike

Russia also continues to launch missiles, drones and bombs at cities across Ukraine. At least four people were killed and 27 injured in a Russian missile strike on residential buildings and “civil infrastructure” in the southern Ukrainian port city of Odesa on Monday, regional governor Oleh Kiper said on the Telegram messaging site.

A turreted Gothic-style building known locally as the “Harry Potter Castle” was seen in flames after the strike.

Russia is a far bigger country than Ukraine, with greater resources. It has also received weapon support from Iran and North Korea, the U.S. government says.

Drawn-out Ukrainian efforts to mobilize more troops, and the belated building of battlefield fortifications are other factors currently undermining Ukraine’s war effort, military analysts say.

Nick Reynolds, a research fellow for land warfare at the London-based Royal United Services Institute, said the war “is still largely an artillery duel.”

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He did not expect to see major movement of the front lines in the near term, but siad that “the conditions are being set for which side has military advantage at the front line. The Russian military is in a better position at the moment.

“When we see one side or the other being in a position to move the front line, at some stage, manoeuvre will be restored to the battlefield. Not in the next few weeks, maybe not even in the next few months. But it will happen.”

Delay ‘set the Ukrainians back’: Pentagon

Pentagon spokesperson Sabrina Singh, at a briefing with reporters Monday, also acknowledged Russia’s recent battlefield gains, noting that a delay in congressional approval for additional spending “set the Ukrainians back.”

NATO chief Stoltenberg said more weapons and ammunition for Ukraine are on the way, including Patriot missile systems to defend against the heavy Russian barrages that smash into the power grid and urban areas.

That additional help may be needed as Ukrainian officials say Russia is assembling forces for a major summer offensive, even if its troops are making only incremental gains at the moment.

“Russian forces remain unlikely to achieve a deeper operationally significant penetration in the area in the near term,” the Institute for the Study of War said in an assessment Sunday.

Even so, the Kremlin’s forces are closing in on the strategically important hilltop town of Chasiv Yar, whose capture would be an important step forward into the Donetsk region.

Donetsk and Luhansk together form much of the industrial Donbas region, which has been gripped by separatist fighting since 2014, and which Russian President Vladimir Putin has set as a primary objective of the Russian invasion. Russia illegally annexed areas of Donetsk, Kherson, Luhansk and Zaporizhzhia regions in September 2022.

In other developments, Sophie, the Duchess of Edinburgh made an unannounced visit to Ukraine — the first British royal to travel to the country since Russia’s 2022 invasion.

Buckingham Palace said Monday that Sophie, wife of Prince Edward, met Zelenskyy and First Lady Olena Zelenska in Kyiv and delivered a message on behalf of King Charles III. It did not disclose the timing or details of the visit.

The palace said Sophie, 59, made the trip “to demonstrate solidarity with the women, men and children impacted by the war and in a continuation of her work to champion survivors of conflict-related sexual violence.”