"This crime will not go unpunished," Russia's Defense Ministry had announced Saturday in response to the massive Ukrainian cross-border attacks on Belgorod, which according to the revised death killed at least 24 people and wounded at least 108, including many children at a Christmas market.

Starting Saturday, Russia unleashed its promised 'retaliation' on Ukraine, hitting the Ukrainian city of Kharkiv - which lies just across the border from Belgorod city - with some 50 drones. 

Ukraine's air force said that its anti-air defenses shot down 21 of those drones, but that central buildings were hit and damaged, including apartments, a central hotel, a school, and government buildings.

Regional Gov. Oleh Syniehubov said that 28 people were wounded in the attack on Kharkiv, which is the country's second-largest city. There are reports that a British journalist was among the wounded at the Kharkiv Palace Hotel when it was struck.

According to a statement from Ukraine's military:

The missile strikes, which came as Kharkiv prepared for new year celebrations, were followed by waves of drone attacks on housing blocks. On Sunday, the Ukrainian air force said it had destroyed 21 of 49 Iranian-made Shahed drones that Russia had used to target "the frontline of defense, as well as at civilian, military and infrastructure facilities in the frontline territories."

A Russian military statement claimed the overnight assault only targeted military facilities, including what it called a hotel which housed "foreign mercenaries". 

Kiev responded by calling Russia's version of events "yet another delusional fantasy from the terrorist regime waging a genocidal war against Ukraine," as cited in Euromaidan News.

The Kremlin has meanwhile demanded answers from the Czech government, citing that recovered ammunition and debris from the Belgorod strikes included Czech-made Vampire rockets and Olkha missiles fitted with cluster-munition warheads, according to Associated Press reporting.

It seems Russia may be sending a message suggesting that if Ukraine hits a Russian holiday market, it will hit a Ukrainian hotel just ahead of New Year's celebrations...

Russia has throughout nearly two years of war warned that countries externally supplying weapons to Ukrainian forces would be treated as direct participants in the conflict if their weapons are found to be used against Russia. The US in particular has been the biggest supplier of heavy weaponry, followed by NATO and EU countries.

Moscow has all the while underscored the proxy war nature of the conflict and showdown with NATO, but so far a WW3-style escalation has been narrowly avoided, but this worst case scenario certainly looms large.