Putin’s move tests Biden’s leadership

He threatened to impose the harshest sanctions ever on Russia. He worked to galvanise US allies into a united front. He supplied Ukraine with more weapons than any American president before him. And he beefed up US forces on Nato's eastern flank as reassurance of his commitment.

Despite US President Joe Biden's efforts to head off a Russian attack against Ukraine, President Vladimir Putin was undeterred as his forces invaded in a mass assault by land, air and sea yesterday.

How Biden deals with the unfolding crisis, which Western officials fear could spiral into the bloodiest European conflict since World War Two, is expected to have profound implications for his political fortunes and US relations with the world.

Biden was always going to be limited because his administration made clear it would do whatever it could to help Ukraine defend itself but was not going to put troops on the ground.

His preference for diplomacy and sanctions reflects the scant appetite Americans have for intervention after the Afghanistan and Iraq quagmires.

Putin had the advantage of knowing Biden was not going to war against another nuclear power to protect a country that shared a long border with Russia.

Biden focused instead on coordinating with Nato allies, especially those in the east worried about the spillover from Russia's buildup of 150,000 troops on Ukraine's borders.

Ian Kelly, a former US ambassador to the Organization for Security and Co-operation in Europe (OSCE), said Biden could have sought activation of the Nato Response Force and sent it into Poland and the Baltic states.

Analysts credit Biden with working with allies to prepare sanctions aimed at crippling the Russian economy. He persuaded Germany to freeze approvals for the Nord Stream 2 gas pipeline.

It remains to be seen whether sanctions will get Putin to back down.

Biden's response could also have repercussions for US-China relations. There is concern if Biden appears too soft on Moscow, China could take it as acquiescence to act against self-ruled Taiwan.

Putin's defiance could give US Republicans a cudgel to use against Biden and his fellow Democrats in the November midterm congressional elections, which will decide the balance of power in Washington.

And Biden's strategy leading up to the Russian attack will come under closer scrutiny as he charts the path forward.