Speaking ahead of a NATO summit in the Netherlands with alliance members under US pressure to massively ramp up military budgets, Kallas warned that increased defence spending alone was not enough to deter the Kremlin.

"Today, against NATO and the EU, Russia doesn't stand a chance. But we must stick together," Kallas told the European Parliament in Strasbourg.

"When NATO leaders meet next week, keeping unity in the alliance is as much a priority as spending more on defence."

NATO leaders look set to agree to a major increase in military budgets as they meet in the Hague next week.

But the alliance, which includes 23 of the European Union's 27 member states, has been rattled by questions over the reliability of the United States under President Donald Trump and Washington's commitment to Europe's defence.

On Tuesday, leaders from the Group of Seven nations, which brings together NATO's biggest economies -- Italy, the United States, France, Germany, the UK and Canada -- plus Japan, stopped short of a joint condemnation of Russia for its growing attacks on Ukraine at a summit in Canada, after Trump's early departure from the meeting.

The US president has so far unsuccessfully sought to end Russia's war in Ukraine through negotiations with Moscow.

On Wednesday, Kallas hammered home the warning that Russia's military build-up poses a threat to Europe and transatlantic security.

"Last year Russia spent more on defence than the EU combined. This year, Russia is spending more on defence than on its own health care, education and social policy combined," she said.

"This is a long-term plan for long-term aggression. You don't spend that much on military might if you're not planning on using it."

The EU has launched a raft of initiatives aimed at raising up to 800 billion euros to help member countries bolster their defences.

On Tuesday Brussels unveiled proposals designed to slash red tape to allow Europe's defence industry to bolster production.

"The voices in this chamber only underline how many diverse opinions there are in Europe. But what unites us -- what must keep uniting us -- is a goal to keep our citizens safe," Kallas told lawmakers in Strasbourg.