EU Defence Commissioner Andreas Kobelius has called on member states to act quickly to compensate for any imminent withdrawal of US troops and equipment from the continent, stressing that a delay in bridging strategic gaps could tempt Russia to test European deterrence.

The Lithuanian official's remarks came during a speech on Tuesday to leaders and officials in the defense industry, on the sidelines of the European Defense and Security Summit 2026 held in Brussels.

The loss of vital U.S. strategic capabilities — or what he called enablers — that make military operations possible, including in particular aerial refueling and intelligence gathering from space — will weaken the bloc's position, in areas where Europeans still rely almost entirely on Washington, Kobelius said.

Preparing for NATO 3.0

The European Commissioner expressed support for the "NATO 3.0" vision recently put forward by US Secretary of Defense Pete Hegseth, which is based on Europeans taking the lead in the traditional defense of their territory, while Washington transfers part of its military assets to other regions of the world.

Kobelius warned of the lack of time available, saying that the U.S. transfer of equipment "may not happen in the distant future, but soon."

The calls reflect a new phase of transatlantic relations, coinciding with the Pentagon's announcement last week of a comprehensive review of the U.S. military presence in Europe, expected to last six months, and the United States is constantly pressing its allies to increase their financial contribution to the continent's security.

Strategic gaps and a heavy price for peace

Kobilios estimated the cost of developing the strategic capabilities Europeans need to offset the U.S. withdrawal at around 500 billion euros, far more than the European Commission has proposed for defense spending in its next budget.

Brussels has submitted a proposal for €131 billion for the period between 2028 and 2034, a figure that is still awaiting approval from the European Parliament and member states.

"We must pay the price for peace at the cost of war," Kobelius said, warning that failure to fill in the defense gaps would have more severe consequences.

Europe will be weaker in terms of defense and deterrence unless it can acquire the necessary weapons and capabilities, he said, describing this weakness as "an open invitation for Putin to test us," referring to Article 5 of the NATO Charter, which provides for mutual defense.

Integration of Ukrainian military power into the European system

In another theme of his speech, Kobelius stressed the need to integrate Ukraine into the continent's defense architecture.

He called the Ukrainian military "the strongest and most powerful in Europe," noting that no army in Europe or the United States is capable of fighting a modern war as Kyiv is currently doing.

The Commissioner attributed this advantage to the courage of the troops and the competence of the Ukrainian military leadership.

The European official called for Kyiv to be included in the defence industry market and the bloc's technological base, saying it was difficult to understand how to build a European security system without involving "the most powerful military force on the continent".

Kobelios said European countries would spend nearly seven trillion euros on defense until 2035, in compliance with pledges made last year by NATO allies to allocate at least 5 percent of GDP to military spending.

Transatlantic tensions and Trump's threats

The European warnings come amid rising tensions between Washington and its allies, with US President Donald Trump once again publicly threatening to refuse to provide assistance to NATO countries if they ask for it, in response to the refusal of some allies to support the US military operation in Iran.

Trump said during a news conference at the White House on Monday : "We spent all this money. And then when we want maybe to get help with small things. They say no, we prefer not to help," he said, adding that the refusal of allies to help is "stupidity" because Washington in turn can and may refuse support in the future.

In a post on his Truth Social account on Sunday, Trump criticized Italy's position on the recent war with Iran, saying that after spending trillions of dollars on NATO, Rome and its prime minister did not think of getting involved to confront the Iranian nuclear threat.

"For decades, we have defended them, but when they test, they are not on our side or with the world. That's not good."

Obstacles on the ground and the fate of the alliance

Several NATO member states have rejected the U.S. military campaign against Iran, either by preventing U.S. military aircraft from using their airspace, or by refusing to send naval forces to help reopen the Strait of Hormuz.

Trump has repeatedly called the alliance a "paper tiger" and threatened to pull out of the 32-member alliance in recent weeks, arguing that European allies have relied too much on U.S. security guarantees while providing insufficient support for the U.S.-Israeli campaign against Iran.

Despite this tense atmosphere and fractured relations, President Trump is scheduled to attend next month's NATO summit in Ankara, while the United States announced at a meeting of NATO defense ministers last week that it would conduct a comprehensive review of its military presence in Europe over the next six months, adding urgency to European calls to boost defense self-sufficiency.