Diplomatically, updating the nuclear doctrine has multiple benefits. It makes headlines, looks intimidating, and might (if he’s lucky) make the Americans think twice about the missiles.
It gives ammunition to domestic critics of Mr Biden accusing him of escalating the war, and potentially reinforces president-elect Donald Trump’s message that the war must be ended as soon as possible.
It is also relatively safe: Putin announced the changes in September, so it does not come as a surprise. It’s a document, not a bomb, so it effectively observes the unwritten rule of cautious and incremental tit-for-tats between the US and Russia.
Mr Biden observed the same rule when he waited for North Korea to enter the war before granting Ukraine strike permissions, and did Russia the courtesy of leaking the decision to The New York Times.
So Putin may be content to let things lie.
Tatyana Stanovya, a senior fellow at the Carnegie Russia Eurasia Centre, warned that he may also find further escalation dangerously tempting.
It would expose Biden to further criticism and reinforce Mr Trump’s argument for direct dialogue with Putin, increasing the chances of a settlement of the war on Russia’s terms, she reasons.