European spy chiefs have issued a chilling warning that Russia could be just months away from dramatically escalating its campaign against NATO - potentially through  missile or drone attacks, sabotage or even a limited incursion onto alliance territory.

Senior intelligence officials across the continent are increasingly concerned that Moscow could soon attempt to deliberately test NATO's resolve, with one security chief warning that the danger could materialize in a matter of 'months, not years.'

The alarming assessment comes as European governments grapple with what they say is a growing campaign of Russian sabotage and provocation designed to frighten populations, fracture the alliance and weaken support for Ukraine.

Polish Prime Minister Donald Tusk has told lawmakers that intelligence assessments suggest Russia could launch drones or missiles at NATO territory in the coming months in an attempt to demonstrate that the alliance's crucial Article 5 mutual-defense guarantee is 'more theoretical than practical.'

French President Emmanuel Macron described Tusk's warning as 'sound and well-documented' and on Friday summoned political party leaders and candidates for France's 2027 presidential election to an emergency meeting in Paris, where Russia's growing threat was among the subjects discussed.

But one of the starkest warnings came from Michal Koudelka, who heads the Czech Republic's BIS security service.

Koudelka said Moscow's next move could go beyond the increased drone activity already unnerving European capitals and potentially involve a small-scale incursion into NATO territory bordering Russia.

'It's possible. It could involve a limited incursion, false-flag provocations, a massive influence campaign,' he said in a rare interview at the agency's Prague headquarters.

Asked about the potential timeframe, Koudelka said such a scenario could unfold in 'months, not years,' although he stressed that 'a lot of people are doing everything they can to make sure this doesn't happen.'

The warning comes amid a dangerous period in Russia's war against Ukraine, with both Moscow and Kyiv intensifying their long-range attacks.

Ukraine launched hundreds of drones at Moscow and other Russian regions early on Sunday in one of the largest aerial assaults of the war, while Ukrainian forces have repeatedly targeted Russian oil infrastructure and refineries.

Moscow, meanwhile, has repeatedly claimed that Western nations supplying Ukraine with weapons, intelligence and military assistance have effectively made themselves participants in the conflict.

Yet there is far from unanimity among Europe's intelligence chiefs that a direct Russian attack on NATO is imminent.

Officials in the Baltic states which sit on Russia's doorstep and have spent years warning Western Europe about the Kremlin and are now among those urging caution about increasingly dramatic public predictions.

'We don't see indications of an imminent attack,' said Normunds Mežviets, director general of Latvia's VDD state security service.

Mežviets said there were signs that Moscow was preparing for more decisive action in Europe, but questioned whether those preparations pointed toward an actual military attack or were instead intended to destabilize Western societies.

'It's still an open question if they have direct and concrete plans or if it's just within the context of their overall attempts to spread fear and uncertainty in Western society,' he said.

'We see them looking to attack railway infrastructure, Ukraine support infrastructure. Right now we see a move towards defense industry targets,' Mežviets explained. 

Estonian officials have issued a similarly cautious message.

Jonatan Vseviov, secretary general of Estonia's foreign ministry, warned on Saturday against 'panic on social media' over suggestions that an attack could be imminent.

'If there is reason to fear an attack, rest assured: we will make that clear. Until then, keep calm, carry on and support Ukraine,' he wrote.

The caution marks a striking reversal for Baltic countries that spent years warning other European governments that they were dangerously complacent about Moscow.

'Before 2022, we constantly warned our Western European partners about the threat from Russia, but most of the time our voices were not listened to,' Mežviets said.

After Russia's full-scale invasion of Ukraine, he said, that changed: 'They said it turns out the Balts and the Poles had been right.'

In the months before Vladimir Putin ordered the full-scale invasion, US officials repeatedly warned that Russian forces were preparing to attack Ukraine. 

Moscow repeatedly rejected those warnings before ultimately launching the assault.

The Kremlin is again denying that it intends to attack NATO.

Following CIA Director John Ratcliffe's surprise trip to Moscow last month, Kremlin spokesman Dmitry Peskov dismissed speculation that Russia could attack the alliance.

'It has nothing to do with reality and nothing to do with the intentions of the Russian Federation,' Peskov said.

European intelligence officials are particularly concerned about the escalating sabotage campaign they attribute to Moscow.

Western agencies have accused Russia of using covert operations, arson, sabotage and drones against European targets while stopping short of the kind of overt military attack that could trigger a united NATO response.

Koudelka described Moscow's approach as 'escalate to de-escalate' - pushing Western countries hard enough that they begin reconsidering their support for Kyiv.

'They believe if they escalate enough, then European countries will decide not to support Ukraine,' he said.

The objective, intelligence officials believe, may be as psychological as it is physical - disrupting support for Ukraine while making Europeans feel increasingly vulnerable.