There were long queues of cars at checkpoints in Mariupol yesterday morning. Many were filled with families fleeing the city, which lies in south-east Ukraine, after Russian troops crossed the border and turned up nearby. Meanwhile the city’s civil defence chief issued those residents who remained with tips for avoiding shrapnel damage, as another city prepared for Putin’s war.

This new front opened up last week, following a period of success for the Ukrainian military in winning back land from the insurgents who, for months, have been tearing apart their country. The fear now is that the rebels will attack first this strategically important port of 400,000 people, then crack open a land corridor to occupied Crimea and possibly even beyond that to Transnistria, the pro-Russian region of Moldova.

Ukraine’s president, Petro Poroshenko, is right to say his nation is the victim of “military aggression and terror” as he warns of being close to full-scale war with Russia. Remember that for all the Kremlin propaganda and bilge spewed out by supportive Western dupes, Poroshenko’s people desire only the peace, prosperity and freedom we take for granted. Yet in response to Putin’s invasion Western democratic leaders - perhaps dazzled by the scale of global challenges - have done little more than talk tough.

Their failure is symbolised by verbal acrobatics as they avoid using the word “invasion”, talking instead of “incursion” and “aggression.” This is echoed by many in the media. Yet Russia invaded Ukraine in February when “little green men” grabbed Crimea, the first such annexation on mainland Europe since 1945. Then we saw Russian citizens lead separatist movements in eastern Ukraine, along with incontrovertible evidence othat they were aided by Russian troops, tanks and artillery - including the weapon which shot down a civilian airliner.

Like other journalists, I met Russian soldiers in Donbass who readily admitted their nationality. Western defence sources think there may be as many as 5,000 troops now in Ukraine, with another 20,000 on the border. Russian paratroopers have been captured; a major convoy of tanks crossed into Ukrainian territory; troops brag online about ‘occupying’ Donetsk.

So let us stop playing Vladimir Putin’s games and start facing facts: he has sent Russian forces into another country and is willfully ripping apart a European nation. His ambitions may even be clarifying with talk of “Novorossiya” (New Russia), whose flag these rebels are suddenly flying. Putin pointedly used this loaded term on television last week; it refers to lands ruled by Catherine the Great that cover one-third of modern Ukraine.

We should not be surprised by Putin’s actions. As his biographer Masha Gessen points out, clues to the nature of his regime were evident within weeks of taking office. Six of the first eleven decrees he issued concerned the military, with defence spending increased 50 per cent despite deep economic problems, while just months later he had destroyed two of his wealthiest rivals and seized control of the three main federal television networks.

Under his rule we have witnessed the devastation of Chechnya in response to dubious “terrorist” attacks, followed by the carving out of a rump state from Georgia. Driven by panic at the eruption of democracy in Kiev, Putin is now all the more dangerous as a result of the soaring popularity this latest campaign has brought him. In Moscow there is even extremist talk of testing Nato weakness with strikes on Baltic states.

So how can we respond to this former KGB apparatchik with Tsarist ambitions? Siren voices - some enjoying the fruits of Russian oil revenues - propose giving in to Putin’s demands by abandoning Crimea, creating vassal states, lifting tepid sanctions and preventing any “humiliation” of a gangster president. Diplomacy must be pursued - yet it is difficult to have faith in negotiations with a ruler who has lied so brazenly and consistently.

Ukraine crisis: Civilians targeted in Donetsk Show all 11 1 /11 Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis An injured man hugs a woman as they sit in an ambulance after shelling in the main separatist stronghold of Donetsk, eastern Ukraine. Three civilians had been killed in shelling in eastern Ukraine's Donetsk, where Kiev's army is fighting pro-Russian separatists, AFP correspondents saw AFP PHOTO / DIMITAR DILKOFF Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis Local residents sit in a basement used as a shelter from artillery fire, in the settlement of Makiivka, on the outskirts of Donetsk. Artillery fire could be heard on Tuesday in Makiivka, on the eastern outskirts of the rebel-controlled city of Donetsk, Reuters reporters at the scene said REUTERS/Maxim Shemetov Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis Pro-Russian separatist troops run away from a burning car after Ukranian army shelling in Donetsk, Ukraine EPA/VALENTIN EGORSHIN Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis Ukrainian soldiers park their hardware on roadside as they are waiting for the start of the march into the town of Mariupol, eastern Ukraine. Heavy shelling hit a town of Novoazovsk in southeastern Ukraine on the third day of an assault that has forced government troops to spread their ranks thinner along the Russian border AP Photo/Sergei Grits Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis The body of a woman lies on the ground after a shelling in the main separatist stronghold Donetsk. Three bodies, identified by bystanders as members of the same family, were seen in a residential neighbourhood east of the city centre DIMITAR DILKOFF/AFP/Getty Images Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis Ukrainian soldiers park their hardware on roadside as they are waiting for the start of the march in the town of Mariupol, eastern Ukraine AP Photo/Sergei Grits Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis Armed pro-Russian separatists speak with local residents on a street in the settlement of Makiivka, on the outskirts of Donetsk REUTERS/Maxim Shemetov Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis A car burns after Ukranian army shelling in Donetsk, Ukraine. Ukrainian President Petro Poroshenko said on the sidelines of a summit in Minsk that he wanted to find a compromise to end the bloodshed that includes the interests of the people in eastern Ukraine EPA/VALENTIN EGORSHIN Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis Local residents wait in a basement used as a shelter from artillery fire, in the settlement of Makiivka, on the outskirts of Donetsk REUTERS/Maxim Shemetov Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis An armed pro-Russian separatist checks papers of a local resident on a street in the settlement of Makiivka REUTERS/Maxim Shemetov Ukraine crisis: Civilians targeted in Donetsk Ukraine crisis A paramedic assists an injured man after shelling in the main separatist stronghold of Donetsk. German Chancellor Angela Merkel pushed for a new ceasefire in crisis talks with Ukrainian President Petro Poroshenko as a controversial Russian convoy returned home DIMITAR DILKOFF/AFP/Getty Images

Moscow calculates that its deceptions inflame divisions in Nato and the European Union, especially given its web of energy, financial and trade links. The West should respond with strong fiscal support for Ukraine plus unified sanctions that cut off financial arteries and hit Putin’s pals far harder; why, for example, have prominent football club owners evaded the blacklist despite close links with the Kremlin?

Nato must strengthen both itself and the frontline states at its Welsh summit this week, while the coalition should urgently review slashing back Britain’s armed forces. These are alarming times again in Europe and the warning has to be clear: Putin is turning his great nation into a pariah state. There may be repercussions: winter - Russia’s traditional ally - is soon arriving when Ukraine alone needs five billion cubic metres of gas.