LONDON/BRUSSELS - Military chiefs from some 30 countries gathered in Britain on Thursday to discuss how the so-called "coalition of the willing" might function in practice to defend Ukraine in the future.

"Everybody wants a peaceful outcome, a lasting peace, not least the Ukrainians. But that will only be lasting...if there is security arrangements in place to ensure that if there is a deal, it is a defended deal," British Prime Minister Keir Starmer said at the close-door meeting at the Northwood military base outside London.

Britain has taken a leading role in organizing Western support for Ukraine alongside France after US President Donald Trump surprised Europe by initiating talks with Russian President Vladimir Putin.

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Starmer noted that previous meetings involving international political leaders had established a consensus that "we need to work together to ensure that any deal that is put in place is defended."

"What's happening here is turning that political intention into reality. The concept into the plans, whether that's in relation what might happen on the sea, air or on the ground," Starmer said.

Starmer's comments reflected the shift toward an operational phase, The Guardian reported, citing a Downing Street source.

"The purpose of these security arrangements is to make it clear to Russia that any breach of an agreement will carry severe consequences," Starmer told reporters after the meeting. "That is why US involvement will be necessary," he added.

Countries represented at the meeting included France, Poland, the Netherlands, Romania, Canada, Australia, and the United States, according to The Guardian. However, the United States has so far declined to commit to supporting any Western military presence in Ukraine.

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In response, the Kremlin on Thursday accused European countries of seeking "militarization" rather than peace.

"Europe has embarked on a militarization of itself and has turned into somewhat of a war party," Kremlin spokesman Dmitry Peskov told reporters.

Meanwhile, the next round of Russia-US talks on Ukraine is scheduled to take place on Monday next week in Riyadh, Saudi Arabia, Russian presidential aide Yuri Ushakov said on Thursday.

On Tuesday, Trump and Putin held a phone conversation, agreeing on an initial step toward peace in Ukraine. However, Kyiv has reiterated its demand for direct involvement in peace talks, with major European countries reaffirming their support for Ukraine's stance. 

Separately, Ukrainian President Volodymyr Zelensky on Thursday urged European Union leaders to promptly approve a package of at least 5 billion euros ($5.45 billion) for artillery shells.

Addressing Thursday's EU summit via video link, Zelensky stressed the need for rapid decision-making, urging European leaders to take decisive action in continued support for Ukraine.

He criticized the obstruction of EU decisions.