A move by Lithuania to hurt Russia by barring the rail transit of certain goods to a Russian exclave is evidence of how the West is fighting Moscow under the threshold of all-out war.
Moscow reacted with outrage, warning it would take unspecified actions against Vilnius if the cargo restrictions on trains travelling in and out of Kaliningrad are not lifted.
This does not most likely mean the Kremlin would launch a conventional military attack not least because Lithuania is a member of NATO.
President Vladimir Putin knows such an escalation would put his country into direct conflict with the 30-strong trans-Atlantic alliance.
However, he has a swathe of options in a grey zone of harm that sits in between war and peace, though is not as overtly aggressive. This could include more cyber attacks, new attempts at disinformation operations or specific sanctions.
It’s an area where both NATO allies and Moscow have been attacking each other for years but with far greater intensity in the wake of Russia’s invasion of Ukraine, which is not a NATO member.
The European Union has imposed crushing sanctions on Russia over Ukraine. It is a form of economic warfare, with Moscow hitting back in kind, including by restricting the flow of oil and gas.
Lithuania said it was merely implementing the new EU rules by choosing to block the transit of sanctioned goods, such as steel, travelling to and from Kaliningrad via the only railway line connected to the territory. It means the only way for Russia to supply the territory now without worrying about EU sanctions is via the sea.
Kaliningrad, home to some 430,000 people, is surrounded by Lithuania and Poland, also an EU country.
Vilnius will be fully aware of possible retaliatory steps by Moscow. But Russia would be wary of going too far and triggering a response by the entire NATO alliance, despite its menacing rhetoric.