Britain’s Finance Minister pledged his government would “strike back” at cyberattacks as he outlined the U.K.’s 1.9 billion-pound ($2.3 billion) plan to counter state-sponsored hackers.

“If we do not have the ability to respond in cyberspace to an attack which takes down our power networks, leaving us in darkness, or hits our air traffic control system, grounding our planes, we would be left with the impossible choice of turning the other cheek and ignoring the devastating consequences or resorting to a military response,” Chancellor Philip Hammond said at a technology conference in London.

“We will not only defend ourselves in cyberspace, we will strike back in kind when we are attacked,” Hammond added.

The spending over the next five years represents a doubling of funding on cyberdefense in the 2011 to 2016 period, according to the government.

While Hammond did not mention specific countries the U.K. considers threats, his speech came as the head of the U.K.’s internal intelligence agency accused Russia of pushing its foreign policy in increasingly aggressive ways, including through cyberattacks.

“Russia is using its whole range of state organs and powers to push its foreign policy abroad in increasingly aggressive ways - involving propaganda, espionage, subversion and cyber-attacks. Russia is at work across Europe and in the U.K. today,” MI5 Head Andrew Parker told The Guardian newspaper.

“Russia has been a covert threat for decades. What’s different these days is that there are more and more methods available,” Parker added.

The Guardian said it was the first newspaper interview given by a serving MI5 chief in the organization’s 107-year-history.

Moscow responded swiftly to Parker’s comments with Reuters quoting Kremlin spokesperson Dmitriy Peskov as stating ‘those words do not correspond to reality.”

“Until someone produces proof, we will consider those statements unfounded and groundless,” Pekov added.

British relations with Russia have suffered in recent years, after the annexation of Crimea in 2014 and the ongoing conflict in Syria.

Russia has also been accused of using cyberespionage tactics to interfere with the U.S. election.

The Obama administration last month blamed Russia for a wave of email hacks, including on figures closely linked to Democratic presidential candidate Hillary Clinton’s campaign.