There's more than one way to intimidate your neighbor.
Last week, for example, Moscow announced that it was temporarily closing the Kerch Strait to all maritime traffic except for Russian naval vessels -- effectively cutting off southeastern Ukraine's access to the Black Sea.
This time, the closure lasted just for a day. The stated reason was to facilitate construction work on a controversial bridge across the strait linking the illegally annexed Crimean Peninsula to Russia.
But according to Russian media reports, there are plans to close the strait for more than three weeks in August and September.
And if this happens, the strategically important port cities of Mariupol and Berdyansk would be cut off from international trade, heavily damaging the Ukrainian economy.
Russia's closure of the Kerch Strait is essentially a double violation of international law.
It would violate a 2003 agreement between Moscow and Kyiv giving vessels from both countries free access to the strait.
And the only reason Russia has the ability to unilaterally close the strait, the only reason Moscow controls both sides of the passage, is, of course, the illegal occupation and annexation of Crimea.
Russia's closure of the Kerch Strait is yet another way for Moscow to send the same message to Kyiv that it has been sending for years: We can -- and will -- make your life miserable in oh so many ways.
It's yet another message that the Kremlin views Ukraine's sovereignty as limited and conditional.
Moscow is telling Kyiv that what's mine is mine and what's yours is mine.
And this goes for Ukraine's territory, as well as its territorial waters.
There are, indeed, many ways to intimidate a neighbor.