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A Kremlin adviser is warning that UK factories making drones and missile components for Ukraine could be attacked by “unknown sources,” days after the UK cleared the way for Kyiv to start building long-range cruise missiles of its own.

Some shit you should know before you dig in: UK Prime Minister Andy Burnham made Ukraine his first overseas trip, arriving Monday for the 35th anniversary of the country’s independence. He brought an agreement clearing British defense firm MBDA to release the classified designs for the UK-built parts inside the SCALP, France’s version of the Storm Shadow, so the missiles can be assembled in Ukraine. The SCALP has a range of about 150 miles and can hit hardened targets like bunkers and command posts that Ukraine’s own Flamingo cruise missiles cannot.

What’s going on now: Andrei Fedorov, a Kremlin adviser and former deputy foreign minister, told BBC Newsnight that both the Russian press and the Russian public are pushing Putin to hit back at the UK, and that at some point the response may stop being verbal.

“There might be different political steps, and I cannot exclude 100% that there might be some semi-military,” Fedorov said. Asked what that meant, he said, “Something might happen with enterprises, with the factories which are producing drones for Ukraine. They could be attacked, not by Russia, but by… from unknown sources.”

He floated cyberattacks as another option, again from sources Moscow would never officially claim as its own. He also said the Kremlin reads the decision to share the designs as the UK entering the fighting outright, in a war he claims no longer stops at Ukraine’s border. Kremlin spokesman Dmitry Peskov had said Monday that Britain “methodically and regularly adds fuel to the fire” and that Russian forces are now working out where inside Ukraine the missiles would be built, so the sites can be hit.

The threat is not hypothetical. Western intelligence sources told The Telegraph that Russia has launched a fresh wave of covert attacks on European arms factories. Plants in Italy, Bulgaria, and Estonia that produce drones and ammunition for Ukraine have been hit by unexplained fires and explosions in recent weeks. Those sources say Russia has been recruiting local gang members to carry out the attacks, deliberately keeping the operations below the threshold that would trigger NATO’s Article 5.

This all comes as Burnham is expected to travel to New York next month for the UN General Assembly, his first US trip as prime minister, to lobby Trump directly on Ukraine’s defense needs.