The prime minister rarely addresses the nation, but Russia’s decision to conduct a full scale invasion into Ukraine has made this a moment that will be marked in history – the start of the largest conflict in Europe since the Second World War.

“Our worst fears have now come true and all the warnings have proved tragically accurate,” Boris Johnson said.

“President Putin of Russia has unleashed war in our European continent.”

Live updates as Russia launches invasion of Ukraine

The peace in Europe that we have come to take for granted for decades is no longer guaranteed and hundreds of millions of people across the European continent waking up to a new reality.

And in the east of Europe, terror has been unleased. Ukrainians this morning have been fleeing the capital Kyiv as NATO member Lithuania declared a state of emergency and sent the army to defend its border.

Meanwhile, allies have been mobilising, with the EU and US announcing plans this morning that further sanctions would be agreed in the coming hours, and NATO announcing further military reinforcements for eastern allies.

And as for our prime minister, his message was three-fold.

First, he sought to reassure allies and Ukrainians that the UK will not look away as the UK stood squarely with Western allies.

Mr Johnson signalled that the UK and allies would be resolute in making sure President Putin’s venture would fail.

“If the months ahead are grim and the flame of freedom burns low,” he said, “we will make sure it blazes bright again”.

Second, he, like Ukraine’s President Volodymyr Zelenskyy, sought to appeal directly to the Russian people over the heads of their leaders.

He warned them that President Putin had agreed a “tidal wave of violence against a fellow Slavic people” that will end with Russian soldiers losing their lives as he asked them if they really wanted to become a “pariah” state under the regime of Russia’s president.

“I cannot believe this is being done in your name,” he told them.

And finally the promise of further sanctions – the ratchet mechanism, as his Foreign Secretary Liz Truss put it the other day.

Mr Johnson said there would be a “massive package of sanctions designed to hobble the Russian economy”, the details of which MPs will be waiting to see outlined in the House of Commons later today when the PM addresses parliament.

Some MPs call for air support for Ukraine

But also there are clearly now questions about what additional military assistance might be given to Ukraine.

Already some MPs, such as former cabinet minister David Davis, are saying it’s time for NATO to give air support to Ukraine in light of the Russian invasion.

Undoubtedly some will wonder whether that is what the prime minister was alluding to when he said: “Our mission is clear diplomatically, politically, economically and eventually militarily. This hideous and barbaric venture of Vladimir Putin must end in failure”.

But I understand the PM’s reference to military action in the address was instead a reference to Ukraine’s own military resistance to the invasion.

Even if that is the case, it is clear the UK and its allies are clear-eyed about how serious the risk now is of a military confrontation that expands well beyond Ukraine and could drag the continent into a long, bloody and protracted war.