The U.S. has warned its allies that Russia is targeting cargo shipping companies as it seeks to disrupt Ukraine’s partners, according to people familiar with the matter.

While Russia has focused cyberattacks and other so-called hybrid actions on shipping firms and ports before, its hostile actions are evolving with intensified sabotage as Moscow’s appetite for taking greater risks increases, the people said, asking not to be identified discussing private assessments. They declined to provide specifics or the scope of Russia’s possible targets.

A U.S. official said that when new information about potential threats becomes available it is shared with allies. 

A spokesperson of the U.S. National Security Council declined to comment. The Russian Foreign Ministry did not reply to a request for comment. 

Russian intelligence targeted several European countries with sabotage attacks, often by hiring local criminals, officials previously told Bloomberg News. Its cyber and disinformation operations have long focused on the U.S. and Europe.

Incidents attributed to Moscow have escalated in recent months to include arson, vandalism, the jamming of GPS signals and a foiled plot to assassinate the CEO of a German arms company. Russia has denied targeting the west with acts of sabotage.

Last year, pro-Russia hackers targeted ports in Europe and Japan. The Asian nation’s biggest maritime port was hit by ransomware — used by hackers to lock access to files or systems unless a payment is made — causing a container terminal to suffer an outage and delays in shipments, while the websites of several Dutch ports fell victim to Russia-aligned hackers.

According to the DPA press agency, German authorities sent a security notice to logistics and aviation companies last month warning them of “unconventional incendiary devices” delivered via freight service after several incidents in which parcels sent by private individuals in Europe caught fire. Russia is not mentioned in the notice, DPA reported.

Russian President Vladimir Putin’s recent threats to NATO countries over Ukraine potentially using western-made missiles to hit military targets in Russia would likely include increased sabotage, cyber and other hybrid attacks, Bloomberg News previously reported.