Iran is increasing efforts to target more sensitive locations in Britain, including military installations, while Russia is expanding its hybrid warfare operations against countries supporting Ukraine, according to the head of Britain’s domestic intelligence service.

In his annual address outlining the security challenges facing the United Kingdom, MI5 Director General Ken McCallum also warned that the most alarming potential misuse of artificial intelligence involved terrorists using the technology to develop biological weapons or engineer entirely new pathogens.

McCallum said threats posed by hostile states have quadrupled over the past decade. As a result, MI5 is now allocating more resources to countering state-backed threats than it did during the Cold War.

On Monday, British Prime Minister Andy Burnham said Tehran was “highly likely” responsible for a suspected plot targeting RAF Fairford, a British air base previously used by American bombers to conduct strikes against Iran. The incident triggered a major security response and prompted US President Donald Trump to withdraw aircraft from the base.

McCallum declined to discuss the Fairford case because the investigation remains ongoing. However, he pointed to a significant change this year in “Iranian ambitions to come at harder targets, like military sites.”

“The RAF Fairfield incident… is not unique. There have been other examples, not just in the UK but around the world,” he says.

Turning to Russia, which also rejects allegations that it has carried out hostile operations in Britain, McCallum described Moscow as the “aggressor number one.”