He joined foreign ministers and diplomats from Italy, France, Germany, Britain, Poland, Spain, Ukraine and the EU to discuss defence spending and their support for Kyiv, as Russia escalates its bombardments.

The meeting of the so-called "Weimar+" group comes ahead of a G7 summit in Canada on June 15-17, where allies will push US President Donald Trump to be more aggressive in punishing the Kremlin.

It will be followed by a NATO meeting in The Hague on June 24-25, where the focus will be reaching a deal that satisfies Trump's demands to spend five percent of GDP on defence.

Rutte is urging NATO members to commit to 3.5 percent of GDP on direct military spending by 2032, and an additional 1.5 percent on broader security-related expenditure.

"We are discussing the final decisions we will take in The Hague. I'm pretty confident indeed... that we will get to a joint position, all 32 (members)", he told reporters heading into the talks in Rome.

He praised Trump's efforts to reach a peace deal in Ukraine by talking directly to Russian President Vladimir Putin, saying "he broke the deadlock" -- even if the discussions are stalled.

Russia has fired record numbers of drones and missiles at Ukraine over recent weeks, escalating three years of daily bombardments as it outlines hardline demands -- rejected by Kyiv as "ultimatums" -- to halt the war.

Rutte noted that Russia had sent a historian to talks in Istanbul, "explaining more or less that Ukraine is at fault here. I think that's not helpful, but at least, step by step, we try to make progress".

Italian Foreign Minister Antonio Tajani, the meeting host whose country spends 1.5 percent of GDP on defence, said he was "very happy" with Rutte's spending plan.

"For Italy it's important to spend more but we need more time, 10 years, I think it is more or less possible to achieve this goal," he said.