Briefly raised hopes of averting a “horrendous” war in Ukraine are fading again after the US predicted an invasion in the “next several days” and British officials said they believed Vladimir Putin, Russia’s president, had decided to attack.

The mood in Washington and London had shifted abruptly after Russian-backed separatists shelled Ukrainian targets in the disputed eastern Donbas region. Moscow claimed Kyiv’s forces opened fire first. Clashes are continuing.

US president Joe Biden said that Russia was “engaged in a false-flag operation to have an excuse to go in” and was increasing, not reducing, troop numbers. That analysis was echoed in other Nato and EU countries, which are preparing punitive sanctions. Diplomatic efforts to halt the slide to war are not yet exhausted. Antony Blinken, the US secretary of state, is due to meet his Russian counterpart, Sergei Lavrov, in Europe this week – assuming there is no invasion.

They will discuss Russia’s demands, delivered in writing last week, for a Nato withdrawal from eastern Europe and curbs on US missile deployments. Lavrov will also insist Ukraine be permanently denied Nato membership.

In the documents, which are a formal response to American proposals for continued dialogue, Russia warns it will be forced to take measures of an unspecified “military-technical character” if its concerns are not addressed.

Western leaders, including Boris Johnson, Kamala Harris, the US vice-president, Olaf Scholz, Germany’s chancellor, and Ukraine’s president will discuss the crisis this weekend at the annual Munich security conference. Unusually, Russia and China will not attend.

Meanwhile, global stock markets reacted badly to increased fears of war, with share prices falling sharply. Gloom about the prospects for peace overwhelmed a midweek surge of optimism, sparked when predictions that Russia would invade last Wednesday proved wrong. Instead, Putin said he was pulling back some forces from Ukraine’s border.

It seemed catastrophe had been averted. Yet within hours US and Nato officials were claiming the pullback was illusory. The White House flatly accused Russia of lying, saying troop numbers have swelled to around 150,000.

For his part, Putin alleged, without evidence, that “genocide” against ethnic Russians was under way in the Donbas – another possible pretext for invasion. He continues to insist his troops are withdrawing and that there is no intention to attack

Who and what to believe? The next few days could be a turning point. Or the stand-off could drag on inconclusively for months. The only certainty is that the future of Ukraine, and of relations between Russia and the west, hangs in the balance this weekend. Although an armed invasion has not yet happened, the 2022 “war for Ukraine” is already being waged on multiple non-military, political, diplomatic, economic, technological and covert fronts. So who’s winning so far?

Vladimir Putin

The question on everyone’s lips: what does Putin want? One theory is this former low-level KGB officer and part-time taxi driver has a massive chip on his shoulder.

He has a small man’s visceral need to prove his (and Russia’s) superiority to the western victors of the cold war – but also to the former Soviet elites, from whose ranks he was excluded.

A less complex explanation is that Putin views Ukraine as an integral part of historical Russia and Ukrainians and Russians as one people. He claims Ukraine is not a real country. For him, re-absorption into the fatherland is natural and logical, while efforts by Kyiv’s leaders to align with the west are anathema.

Experts say Putin is intent on recreating the supposed glories of the Soviet era. He calls the collapse of the Soviet Union a geopolitical tragedy.

Looked at this way, a conquest of Ukraine is part of a larger scheme to rebuild a Russian sphere of influence encompassing eastern Europe and central Asia.

More mundanely, Putin’s actions can be explained by genuine fear that Russia’s security is threatened, his (disputed) belief that Nato broke a pledge not to expand up to Russia’s borders, and concern that it may accept Ukraine’s membership. Putin, a de facto dictator, feels threatened by a pro-western, democratic Ukraine on his doorstep.

Is he winning? Putin has succeeded in forcing the west to consider his security concerns. He has intimidated Ukraine. And he has reminded a rattled Europe of its dependency on Russian gas.

At the same time, he has hugely reinvigorated Nato, permanently changed western security assumptions, united the US and Europe against him, and reinforced Russia’s reputation as a rogue state that ignores international law and breaks its word.

Joe Biden

The US president was relatively quick out of the blocks over Ukraine. He needed to be. Last year’s chaotic US troop withdrawal from Afghanistan and the resulting damage to Nato’s credibility were laid at his door. With Covid and economic woes already hurting his domestic approval ratings, Biden could not afford a repeat foreign policy disaster.

Having made promotion of democracy and human rights around the world a key foreign policy objective, Biden could also not stand back as Russia threatened a free, independent, democratic state.

Biden’s approach to the crisis is influenced by two additional strategic factors. One is his aim to reboot the transatlantic alliance, undermined by his predecessor Donald Trump. The other is his desire to demonstrate to China, Russia’s ally, that the US will stoutly support its friends, be they in Ukraine or Taiwan.

Biden has sent US troops to reinforce Nato’s eastern flank, assured Kyiv of non-military US support, and stiffened European backbones via an intense diplomatic offensive. In an unusual step, the US continues to disclose detailed (mostly unsubstantiated) intelligence about Russian intentions in an apparent attempt to pre-empt and forestall Putin’s next move.

Biden’s tactics may have succeeded in heading off an invasion until now. There are two large caveats. One is that Washington’s attempts to find a diplomatic solution have struggled, while its tough stance may have compromised European efforts. This vacuum is dangerous. The other big reservation is that Biden controversially vowed from the start that US forces would not fight to defend non-Nato Ukraine – despite past US interventions in non-Nato Iraq, Afghanistan, Syria and elsewhere.

Putin could yet take catastrophic advantage of this most un-American display of caution.

Volodymyr Zelenskiy

Ukraine’s president impressed world leaders in the Munich security conference this weekend with a brave and punchy speech after ignoring warnings to stay at home for fear of a Russian-inspired coup attempt. His response to the unfolding crisis has surprised some in the west. Criticising alarming claims in Washington and London about an “any day” invasion, Zelenskiy said such suggestions risked causing panic and harming his country’s economy. As Russian military pressure increased last week, the official tone in Kyiv shifted. But by and large Ukrainians appear unimpressed by frantic talk of war. A “day of unity” last Wednesday – the supposed invasion D-day – was not widely supported. As western diplomats and nationals hastily evacuate, most Ukrainians are firmly staying put.

One explanation is that people have learned to live with threats from Russia. Low-intensity conflict with Russian-backed Donbas separatists has become the new normal since 2014, when Moscow annexed Crimea. Last week’s passage of a resolution in the Russian Duma (parliament) supporting independence for the breakaway Donetsk and Luhansk “people’s republics” in the Donbas was an attempt to increase Putin’s leverage. Such a unilateral move would spell the end for the so-called Minsk accords, whose terms are disputed by both sides.

Ukraine’s aspiration to join Nato lies at the heart of the crisis. Zelenskiy is being pressed by European governments to drop this objective, a key Russian demand, and adopt a neutral, non-aligned status. So far at least, the Kyiv government, cast in the role of underdog, has benefited from increased international support, weapons deliveries and financial aid. It says any war would be about Europe’s future, not just Ukraine’s.

True or not, Ukrainians will be the big losers if Putin resorts to force.

Emmanuel Macron and Olaf Scholz

Emmanuel Macron, the French president who also holds the rotating presidency of the EU council of ministers, has thrust himself into the diplomatic frontline. As the Americans and Russians haggled over Moscow’s demands for new security arrangements in Europe, Macron met Putin in Moscow and sketched possible compromises.

These ideas, including recognition of Russian concerns about Nato expansion, its forward deployments in eastern Europe, and current and future US missile capabilities in Poland and Romania, may yet provide the basis for a deal. Macron also raised the possibility of Ukraine adopting neutral status, not unlike Finland during the cold war.

Macron publicly supports the US-orchestrated plan to impose severe sanctions on Russia should it invade, and insists he acts in close consultation with Washington. But his Moscow talks raised eyebrows. British officials accused him of appeasement and of undermining the west’s united front.

While Macron can shrug off criticism from London, he needs the backing of Germany, the biggest European player. But Olaf Scholz, its newly elected chancellor, has appeared in two minds. On the one hand he wants to salvage the Nord Stream 2 gas pipeline from Russia. On the other he is under intense pressure from Biden to abandon it in support of anti-Kremlin sanctions.

Yet Scholz surprised his critics last week when he met Putin in Moscow. He delivered a feisty performance, raising questions about media freedom and human rights.

That may have reassured hawkish allies such as Poland and the Baltic republics, which have accused him of being “soft” on Russia. At the same time, Scholz extracted a commitment from Putin to continue dialogue in line with Macron’s approach.

The EU commission has been sidelined during the crisis. But the French and German leaders have emerged with reputations enhanced. So far.

Boris Johnson

Beset by scandals arising from illegal lockdown parties and reportedly anxious to change the subject, Boris Johnson seized on the Ukraine crisis in late January after having previously largely ignored it.

At his direction Downing St began briefing about a big, cross-departmental Whitehall push to tackle the crisis. Britain, Johnson claimed, would lead western attempts to deter Russia. But saying it does not make it so. Suggestions that this new effort to aid Ukraine was part of so-called Operation Save Big Dog to rescue his career were denied, naturally.

The UK has since sent extra troops to Estonia, missiles to Ukraine, and placed Royal Navy ships on alert. It is typically iffy about accepting refugees, but has offered humanitarian aid.

But Britain’s emphasis on muscular deterrence has come at the expense of diplomacy. It has contributed almost nothing to peace-making efforts. When Liz Truss, the foreign secretary, met Lavrov in Moscow, their talks ended in an icy standoff.

Johnson has gratuitously undermined Macron’s Moscow initiative while Ben Wallace, the UK defence secretary, spoke disparagingly of a “whiff of Munich”. Meanwhile, the government has yet to enforce effective measures to curb Russian money-laundering in London.

All else aside, the Ukraine crisis has brutally underscored Britain’s diminished international influence abroad. Separated by choice from the EU, the UK is now viewed in Russia (and much of Europe) as little more than a cheerleader and errand boy for America.

When Johnson asked Biden what else the UK could do in a phone call last week, the US president replied: “We’re not going anywhere without you, pal.” That summed up Britain’s war to date. The rule of thumb for post-Brexit foreign policy: ask politely what Washington wants, then follow directions.