A Russian plot to kill one of Europe’s most prominent defense-industry executives signals a significant escalation in Moscow’s covert efforts to sabotage Western weapons production and weaken support for Ukraine, Western officials said.

Earlier this year, the U.S. warned Germany that Moscow had set in motion a plan targeting Armin Papperger, CEO of Rheinmetall, U.S. and German officials said. The German manufacturer of tanks, armored vehicles and ammunition has been integral to Western efforts to support Ukraine as it fights to fend off invading Russian forces.

There was an “intensified threat situation,” especially at the beginning of this year, a person familiar with the matter said. German authorities warned Papperger and ramped up his security, and Russia didn’t follow through with the planned attack, the person said.

A German Interior Ministry spokesman said “the government takes the threat from the Russian regime very seriously.”

He said Moscow was waging a campaign of threats, cyberattacks, disinformation, sabotage and at least one act of terrorism in Germany to weaken Berlin’s support for Kyiv. The spokesman declined to elaborate on the alleged terrorist act.

Russia has been engaged in an intensifying hybrid campaign targeting arms makers, politicians and others across Europe with the aim of undermining military and financial support for Kyiv, Western officials say.

Germany has increased security around Papperger since the start of the year, according to a person familiar with the matter. The CEO now travels with bodyguards, including when attending football matches, while armed police guard the company’s offices when he is there, this person said.

Security has always been an issue for defense companies. Some U.S. defense contractors have in recent weeks tightened security around senior executives, some of whom already travel with armed personal guards. This has included limiting advance notice of public appearances, largely in response to protests against the conflict in Gaza that have disrupted meetings and access to defense facilities.