Russia is “escalating” its hybrid warfare efforts against Europe and its allies as the country’s stalled invasion of Ukraine becomes more costly, the U.K.’s spy chief warned Tuesday.

Ken McCallum, the head of the UK’s MI5 agency, said in a public speech that Vladimir Putin’s Kremlin remains “aggressor number one” in terms of state threats targeting the U.K.

“This means Russia is using tactics that stop short, though sometimes not much short, of conventional conflict. A cyber attack on Polish energy infrastructure. A misfired attempt to use an explosive-laden drone to destroy a cargo plane in Germany. A thwarted assassination attempt in the U.S.,” McCallum said.

“It’s no accident that Russian aggressors are trying to unsettle other European homelands at a time when their military progress in Ukraine is minimal and horrifically costly.”

McCallum said that his agency, which is mandated to safeguard the U.K.’s domestic security, now devotes roughly equal attention to foreign state aggression as terrorism — which he noted is a dramatic shift from the post 9/11 stance of Western security agencies.

McCallum’s warning joins a recent chorus from European politicians, suggesting Russian sabotage and interference operations have increased as the war in Ukraine drags on despite U.S. assurances of an “energy ceasefire.”

Last week, EU foreign policy chief Kaja Kallas told reporters that in recent weeks Europe has seen a spike in “sabotage attempts and airspace violations” attributed to Russia, putting lives at risk.

“Russian missiles and drones violated Moldovan airspace again over the weekend. And this is completely unacceptable,” Kallas told reporters while standing beside Moldovan Prime Minister Vasile Tofan.

It also comes as NATO’s supreme allied commander in Europe, U.S. Gen. Alexus Grynkewich, gave a speech warning against any conventional incursions into the defensive alliance’s territory.

Speaking in Warsaw Monday, Grynkewich said he does not view military conflict in Europe as “imminent or inevitable,” according to French public broadcaster France24.

“If someone is foolish enough to attack us, we will fight. We will stop the attack and deny them the ability to achieve their objectives, whatever those may be … We will, in short, ensure any attack against any ally proves utterly futile.”

In its most recent public report, the Canadian Security Intelligence Service (CSIS) listed the Russian Federation among the countries attempting to interfere in Canadian domestic affairs, behind the People’s Republic of China and Iran.

Russia’s efforts have been aimed at undermining the Canadian government — and people’s — support for Ukraine, the agency suggested.

“Hostile Russian state actors, and those working on their behalf, have carried out several information and malign influence operations against Canada, exploiting various contentious social topics aimed at discrediting the Government of Canada’s position on Ukraine by polarizing segments of both political and public spectrums,” the agency’s annual public report read.

“As part of this, Russian state-linked actors often hide behind networks of proxies who amplify the Kremlin’s messaging or generate their own versions using powerful new technologies, such as artificial intelligence (AI) and social media.”

CSIS noted that, like MI5, the agency has been forced to “reprioritize its operations” in order to counter the activity of “foreign intelligence services and their proxies” who have targeted people in Canada, including thwarting one “potentially lethal” operation.

McCallum noted that Russia’s hybrid tactics do not suggest “a great power with a strategic upper hand” — but said they must be taken seriously.

“The whole aim of hybrid tactics is to intimidate us, so let’s not fall into that trap. But we do need to be resilient to them,” McCallum said.