WHEN, exactly, Russia’s stealth invasion of eastern Ukraine began it is hard to say. That was part of the point of the stealth. But on August 14th the Ukrainian government said it had destroyed a convoy of Russian military trucks carrying ammunition. On August 21st NATO satellite pictures showed Russian military units advancing with self-propelled artillery at Krasnodan on the road between Donetsk and Luhansk. And by August 25th and 26th Russian armoured columns were streaming across the border near Amvrosiyivka, on the road to Donetsk, and at Novoaszovsk, on the coast.

From that point on, the evidence for Russian troops on the ground was clear from the results of the fighting. Earlier in the summer the Ukrainian army had been making progress against the irregular Russian-backed rebels in the east. Now they were being routed by forces that were obviously more professional. The scale of the defeats was dramatic. On September 3rd, Petro Poroshenko, Ukraine’s president, who had been defiant just days before, announced that he had agreed the terms for a “permanent ceasefire” with Vladimir Putin, his Russian opposite number.

Doubtless taking note of Mr Poroshenko’s desperation, the Russian president’s spokesman, Dmitry Peskov, smoothly denied the claim. The two leaders had indeed talked, he said, about “what should be done…to stop the bloodshed” and had found some common ground. But as Russia was not, of course, a party to the conflict, so it was hardly in a position to enter into a ceasefire agreement.

Nevertheless, later that day Mr Putin announced that he had a plan to end the fighting. He said it should be discussed at the meeting in Minsk on September 5th of the Trilateral Contact Group on Ukraine, which comprises envoys from Kiev, Russia and the Organisation for Security and Co-operation in Europe.

All the way to the Black Sea

Mr Putin’s plan requires Ukraine’s armed forces to withdraw from the contested areas in the east of the country, thus confirming the defeat of Mr Poroshenko’s forces and establishing a basis for negotiating some degree of autonomy for the Donbas region. Russia intends “autonomy” to mean that a big chunk of Ukraine stays under its sway. In the meantime, amid few indications of support for a ceasefire on the ground by either side, fighting continued across the east of the country.

Backed by what Ukraine says are four Russian battalion tactical groups—about 1,600 men equipped with modern heavy weapons and air-defence batteries—the separatists have already succeeded in taking back several towns near Donetsk and Luhansk that Ukrainian troops had once held. Luhansk airport, previously a vital bridgehead for government forces, is back in rebel hands. Donetsk airport, which Ukrainian forces have controlled for most of the five-month conflict, could well fall.

And a third front has opened to the south, with the aim of splitting the Ukrainian forces attacking the separatists farther north. On August 27th separatists sent Ukrainian forces fleeing from the border town of Novoazovsk. Ukrainian officials say the attack originated from Russian territory; Kremlin officials deny the charges. Now the insurgents, whose tanks fly the flag of the Novorossiya, or New Russia, the name of their would-be state, have dug in.

Ukraine’s army is no match for the well trained, heavily armed invaders. In the two decades since Ukraine gave up the world’s third-largest nuclear arsenal in exchange for security assurances from Russia, America and Britain, it has spent too little on defence to maintain an effective fighting force. When Russian troops moved on Crimea in March, the defence minister told parliament that the country could field just 6,000 combat-ready infantry troops. The numbers are much higher now—and Mr Poroshenko has announced the reintroduction of conscription—but it is a force that has had to learn on the job, and most of its weapons are from the Soviet era. It lacks basic supplies, including body armour and medical kits.

Poor communication between Ukraine’s regular army and its volunteer militias left several units stranded in the town of Iloviask, not far from Donetsk. Around 700 Ukrainian soldiers were taken prisoner as a result. Semen Semenchenko, the popular commander of the Donbas Battalion, one of the trapped militia units, put a post on Facebook blaming the regular army command. He called for a protest outside the defence ministry in Kiev: “If many-star generals abandoned [the battalion], I believe the people of Ukraine will not.” Over 1,000 protesters showed up.

Rock, Poroshenko, hard place

Rampant corruption and unfettered nepotism mean the defence establishment is riddled with incompetence, and the questionable loyalties of officials held over from Viktor Yanukovych’s rule have led to talk of a “fifth column” within the ministry. Leonid Polyakov, who served as deputy defence minister during the interim administration this spring, says the new administration has yet to take “decisive actions in cleaning house”; but it has changed ministers several times already, adding extra chaos to the dysfunctional mix.

Mr Polyakov believes the country has enough manpower, armour, artillery and light arms to defend itself. But it critically lacks the (more expensive) trappings of a modern army, including secure communications, air power and aerial intelligence. Keir Giles of the Conflict Studies Research Centre, a British think-tank, says that faced with well-trained and recently modernised Russian forces, such as the elite 76th Airborne Division, which appears to be the spearhead for the current operation, the Ukrainians are “up against more than they can cope with”.

In the absence of outside help, a burgeoning Ukrainian civil society has stepped in to help rebuild the army. New charities have raised millions of dollars to supply troops with everything from insulated sleeping bags to first-aid kits assembled by volunteers in Kiev storehouses before being ferried to the front. One such group, Wings of Phoenix, has even started raising money to purchase drones and to refurbish neglected aircraft. On August 30th, it celebrated the take-off of its first sponsored plane, an Antonov AN-26 turboprop which, though spiffily painted, dates from 1979. On the front lines much of the fiercest fighting has fallen to volunteer battalions, whose presence is a double-edged sword. These paramilitary groups bring “great fighting spirit”, says Dmitry Tymchuk, director of the Centre of Military and Political Research in Kiev. The fighters, however, are not beholden to the central government; they purchase their own weapons and supplies. While they have nominally been incorporated into the country’s National Guard, their leaders operate “according to their own plan”, says Mr Tymchuk. The patriotic popular mood the volunteers exemplify puts Mr Poroshenko in a tight spot. Parliamentary elections loom in late October. Mr Tymchuk expects battalion commanders with designs on political power to stand; the battalions are “very strong in Ukrainian society”, says Mykola Sungurovskyi, director of military programmes at the Razumkov Centre, a leading think-tank in Kiev. “Ukrainian independence is sacred for them.” It will be hard for Mr Poroshenko, who has no military background, to sell a ceasefire if the battalions do not back it. He was hardly helped by Arsenyi Yatsenyuk, the prime minister, coming out strongly against Mr Putin’s plan, calling it “an attempt to confuse the international community before the NATO summit and...a wave of new sanctions against Russia”. Mr Yatsenyuk is an ally of Yulia Tymoshenko, a rival of Mr Poroshenko’s for the presidency.

Mr Poroshenko may well agree with Mr Yatsenyuk. But Mr Putin has left him no good options. Faced with the choice of leaving the pro-Russian rebels to wither in their strongholds of Donetsk and Luhansk and ending any remotely plausible deniability about Russia’s role in the increasingly bloody conflict, Mr Putin chose escalation. Having thus committed himself, his message to Mr Poroshenko could not be clearer. Whatever you do on the battlefield, Russia will do more; this is a fight you cannot win. In a telephone call with José Manuel Barroso, the outgoing president of the European Commission, on August 29th, Mr Putin boasted that his forces could take Kiev in a fortnight. Kremlin advisers say the boast was taken out of context—but have offered no context in which it might be a reasonable thing to say about a neighbour’s capital. If in the end Mr Poroshenko chooses to walk away from the ceasefire for which he seemed so eager, he could hunker down for a long drawn-out, low-level war in the hope that it eventually becomes too painful for Russia to continue. But Dmitry Gorenburg of CNA Corporation, a research firm in Virginia, points out that a strategy based on attrition could take years. And if its purpose were to grind the Russians down in place, they might choose instead to spread the conflict.

Partisan possibilities

Were the Russian-backed separatists to advance beyond their current territory, they would probably move first along the coast towards Crimea, or into the central Ukrainian heartland, a region crucial for both countries’ defence industries (until recently, Ukraine produced essential military components for Russia). Such movements would trigger a partisan war, preparations for which have already got under way.

In the port city of Mariupol, half an hour or so west of Novoazovsk, the Ukrainian paramilitary Azov Battalion (whose insignia is a neo-Nazi “wolfsangel”) has begun providing basic weapons training for locals in anticipation of such a breakout. The city is deeply divided. Some of the city’s metal workers say they want rebel rule, others are digging trenches to prevent it. Some who supported the rebels in spring now support Ukraine and vice versa. On August 31st a thick column of black smoke rose above the sea off the village of Bezimenne, as a Ukrainian coastguard cutter blazed after having been fired at from the shore.

The piecemeal invasion is still a far cry from all-out war; Russia could push its military advantage further. But that option will not appeal to Mr Putin. Establishing a land bridge through Mariupol to Crimea would take tens of thousands of troops. So would garrisoning eastern Ukraine. And even Mr Putin’s 84% popularity rating, and his almost-complete control over Russia’s media, do not make him impervious to the effect of the casualties that would follow.

The annexation of Crimea and the war in Donbas have required very few sacrifices from ordinary Russians so far. Encouraged by state propaganda they have supported the war in the same way they support their favourite football team—by watching television, beer in hand. Now that soldiers are starting to come back in closed coffins the mood is changing. The Committee of Soldiers’ Mothers, a group representing the families of servicemen, thinks that more than 200 Russian soldiers have already been killed, 100 from the 18th Infantry Brigade and the rest from the 76th Airborne. Ukraine’s August 13th attack on a Russian convoy, they say, accounted for a lot of these casualties, which Russian authorities have not wanted reported. A council deputy in Pskov, near Russia’s border with Estonia, who publicised the death of soldiers from the 76th Airborne was beaten up by thugs.

Neither the army nor Russian society at large want to see military casualties. According to Levada, an independent pollster, the number of people prepared to support the Kremlin in case of a military conflict with Ukraine has dropped from 74% to 41% since March, while the number opposed has gone from 13% to 43%.

Cursed are the peacemaking outfits

Though Mr Putin has more force that he could bring to bear—Mr Giles says that Russian commanders are preparing a 5,000-strong “peacemaking” outfit based on airborne assault units—he wants to press Mr Poroshenko into a deal on Russia’s terms as quickly as possible. “The demand is that the expansion of Western military and military-political institutions toward the western borders of Russia should be curtailed,” says Sergei Karaganov, dean of the international-relations faculty at Moscow’s Higher School of Economics and an adviser to the Russian government. To many Ukrainians, that will sound like an unacceptable bar on their aspirations to be a full-fledged part of Europe.

Lasting accords will require intensive diplomatic work. A furtive gathering of Russian and American experts and former officials on a Finnish island last month produced an initial plan. It contained 24 points of discussion, demonstrating the breadth of the issues on the table. And even if agreements can be reached between the governments, the presence of militias of varying degrees of independence and bloody mindedness on both sides will make any eventual settlement hard to enforce, notes Andrew Weiss of the Carnegie Endowment in Washington, co-chair of the Finland meeting.

Mr Putin would probably be satisfied either by a settlement that recognised his red lines, such as keeping Ukraine from ever joining NATO, or by a “frozen conflict” like that which holds in Abkhazia and South Ossetia, seized in the 2008 war with Georgia. But Ukrainians have a hard time believing that a compromise, even one on Russia’s terms, would halt Mr Putin’s campaign. And a stalemate offers him endless opportunities to sow more chaos. “We’re playing by Putin’s rules and reacting to his moves,” says Mr Sungurovskyi. “That’s what’s dangerous.”