The Kremlin has put Britain on notice - Russian forces will treat UK soldiers as enemy combatants if they set foot on Ukrainian soil.
Sir Keir Starmer signed a pact with Emmanuel Macron just weeks ago that could see troops from both nations deployed once any ceasefire deal is hammered out.
Moscow pulled no punches on Monday when its Foreign Ministry laid down the law. The "deployment of military units, facilities, warehouses, and other infrastructure of Western countries in Ukraine is unacceptable to us", officials stated.
Any Western military presence would constitute "foreign intervention posing a direct threat to Russia's security", according to the ministry.
The message to alliance members was unambiguous - they need to grasp that "all foreign military contingents, including German ones, if deployed in Ukraine, will become legitimate targets for the Russian Armed Forces."
While issuing warnings to the West, Foreign Minister Sergei Lavrov rolled out the red carpet for President Donald Trump's "purposeful efforts" in pushing for a settlement.
The Kremlin heavyweight lauded Mr Trump as "one of the few Western politicians who not only immediately refused to advance meaningless and destructive preconditions for starting a substantive dialogue with Moscow on the Ukrainian crisis, but also publicly spoke about its root causes."
Washington has taken charge of diplomatic efforts to halt the bloodshed, with another meeting between all three sides planned for the UAE in the days ahead, reports GB News.
Volodymyr Zelensky claimed in his New Year's address that an agreement was "90 per cent" done and dusted, though territorial disputes continue to derail progress.
Moscow's insistence on seizing all of Donbas has been met with fierce resistance from Kyiv.
Ukraine's capital came under Russian bombardment on Monday evening - a matter of days after Mr Trump told the world both sides had stopped fighting.
Vitali Klitschko, Kyiv's Mayor, reported flames tearing through a building with a nursery inside, while another non-residential structure took a direct hit.
Kharkiv - Ukraine's second-largest metropolis - was among multiple locations across the nation that faced incoming fire.
The regional governor put the casualty count at two injured.
Last month's Anglo-French declaration signed in Paris represents a "vital part of our commitment to stand with Ukraine for the long-term", according to Sir Keir Starmer.
He added: "It paves the way for the legal framework under which British, French, and partner forces could operate on Ukrainian soil, securing Ukraine's skies and seas, and regenerating Ukraine's armed forces for the future."
Any American-led ceasefire verification mission will include British involvement, the Prime Minister has pledged.
Following the Paris discussions, US special envoy Steve Witkoff revealed that negotiations of security protocols with Ukraine were "largely finished".
He added: "We are here to mediate and help in the peace process, and we're prepared to do anything necessary to get to that place. President Trump strongly, fervently believes that this killing has to stop, that the carnage has to stop."
