ON JUNE 18th the Ukrainian crisis, which has slid into a nasty and increasingly bloody civil war of late, took a small step backwards to possible de-escalation. After talking to Vladimir Putin, his Russian counterpart, Ukraine’s president, Petro Poroshenko, declared a unilateral ceasefire in the east to give time for anti-government insurgents either to leave Ukraine or to give up their weapons. However, the fighting around Donetsk and Luhansk now has its own self-perpetuating logic, driven by daily skirmishes between rebel militiamen with unclear allegiances and poorly trained, ill-equipped Ukrainian troops. Decisions taken in Kiev, or in Moscow for that matter, may have little effect on the ground.

The insurgents in the east were quick to say they would not abide by the ceasefire. The real danger is that, ever since the fall of Viktor Yanukovych in late February, rational solutions to the crisis in Ukraine have “not been in demand” in Moscow, according to Sergey Utkin of the Department of Strategic Assessment at the Russian Academy of Sciences. Instead of a stable post-Yanukovych Ukraine, the Kremlin appears to prefer a weak country under an ever-present risk of falling apart—or, as Mr Utkin puts it: “A Ukraine that is so occupied with its own internal problems that it doesn’t have time for anything else.” Mr Putin seems to have ignored his own warnings in past conflicts about how anarchic violence knows no borders.

In another twist, Mr Utkin notes, more revanchist and conservative voices in Russian foreign-policy circles have for years accused the Americans of stirring up “managed chaos” around the world as a way of nefariously advancing their objectives. Now those same hardliners are backing a Russian policy aimed at just such a goal in Ukraine. With support that can range from winking approval to proxy deliveries of arms and money, the Kremlin has tried to ratchet up (and down) instability in eastern Ukraine as a way of applying pressure to the government in Kiev, wielding the implicit threat of widespread civil war or even invasion.

In practice that has meant allowing the passage of Russian volunteers into Ukraine to join the fight and giving political cover to separatist leaders like Denis Pushilin and Alexander Boroday, who have been in Moscow for meetings with key figures, including Vladislav Surkov, a longtime master of political sorcery close to Mr Putin. More murkily, some Russian weapons seem to be finding their way to eastern Ukraine, perhaps including an Igla rocket system that was used to shoot down a military aircraft on June 14th, killing almost 50 soldiers, and a handful of Soviet-era T-64 tanks. Rebel fighters are coming under artillery fire, yet they do not have much heavy weaponry, making the tactical logic of arms transfers clear, says Alexander Golts, a military analyst. Yet Mr Golts adds that there are no concrete facts about what is coming from Russia—a sign that the 1,600-kilometre (1,000-mile) border is hard to monitor even with Western surveillance technology.

In recent weeks Russia has tried, with varying degrees of success, to “attach and shorten the leash” over the armed rebels in the east, says Mark Galeotti of New York University. The rise of the Vostok battalion, initially reliant on Chechen fighters and now largely Ukrainian, is an example. Mr Putin would like to consolidate his control over the disparate militia groups, not least so that he can credibly claim to be able to stop the violence as part of a potential “grand bargain” with Mr Poroshenko. The problem, says Mr Galeotti, is that Russian policy has become a “victim of its own success,” in that it has fostered the creation of armed groups and newly empowered warlords who wield more influence than the Kremlin had foreseen. They have their own interests and priorities which do not always align with Mr Putin’s.

The past few days have also seen the re-emergence of another old weapon: natural gas. On June 16th Gazprom, Russia’s gas giant, halted deliveries to Ukraine, because of what it says is a $4.5 billion unpaid bill. The dispute is over price, a subjective measure since Russia charges wildly different amounts depending on its relations with the buyer. (Mr Putin tried to prop up Mr Yanukovych by offering him a cut-rate price of $268 per thousand cubic metres; Gazprom now wants $385.) Even with the taps off, the move was just a warning shot. Ukraine has months before it needs to worry about dwindling stocks for winter, and Russia has its own interests in seeing the gas flow again. Last year more than half of the Russian gas sold to Europe went through pipelines across Ukraine. On June 17th a mysterious explosion damaged one of them. This, and the shut-off, may enable Russia to put pressure on the European Union to permit construction of the South Stream pipeline, now stalled (see story alongside).

All this has taken place against a backdrop of Russian troops rotating to and from the border. They are meant to serve as a reminder to Mr Poroshenko that, lest he think otherwise, his forces cannot achieve a decisive victory on the battlefield alone: he will have to deal with Mr Putin if he wants to pacify the east. The demonstrative presence of the Russian army—several brigades have again moved to the border after some weeks back at base—is also meant to curb temptations in Kiev to resort to heavier weapons, including air power.

Unless he absolutely has to, Mr Putin would much rather not invade. He would prefer to attain his objectives—getting Mr Poroshenko to accept greatly decentralised power in the regions, for example, and to give up hopes of NATO and EU membership—without sending in troops. But if it comes to a choice between invasion, with all its sizeable dangers and costs, and anything resembling an open defeat, which would mean a damaging loss of face at home and abroad, Mr Putin would probably choose to go in.