It’s important to remember that Sunday’s attacks were not a one-off event. Russia has been intensifying the pressure on Ukraine over the past three to four months in small steps, similar to what we saw in Moscow’s creeping aggression against Georgia in the spring and summer of 2008. This may be based on the hope that each small step will be met with nothing more than political protests by the West.

Other Russian actions look ominous in retrospect. In recent months, Moscow has launched incessant artillery and rocket attacks by Russian-led forces on Ukrainian military and civilian targets along the line of contact with occupied Donbas. The Russians have interfered with international shipping to and from Ukraine’s Azov Sea ports of Mariupol and Berdyansk throughout the summer, inflicting significant losses on the local and national economy. The Kremlin imposed sweeping sanctions on Ukrainian companies and pro-Western business leaders earlier this month. The Russians also allowed the holding of elections in occupied portions of the Donetsk and Luhansk districts in flagrant violation of the 2015 Minsk agreements.