Biden hosted Zelensky at the White House in September
Biden hosted Zelensky at the White House in September AFP

Permission from Washington for Ukraine to strike Russian territory with American-supplied long-range missiles may have come too late and hedged with too many restrictions to slow Moscow's advance, experts warn.

US President Joe Biden did not grant Ukrainian leader Volodymyr Zelensky's request for deep strike capability until two months before he hands the keys to the White House to Ukraine aid sceptic Donald Trump.

The shift comes as Russian forces press their advance through eastern Ukraine, claiming on Monday they had captured a new village south of Pokrovsk -- a crucial logistics hub for the defenders.

Moscow's troops took a further 60 square kilometres (23 square miles) over the weekend, according to an AFP analysis based on data from the US-based Institute for the Study of War (ISW).

That brought the figure for November so far to 458 square kilometres -- on track to beat October's total of 610, a record since Russia invaded Ukraine in February 2022.

"Putin hasn't reached the borders of the Donbas. So long as he isn't there yet, he'll keep pushing," a senior French military source told AFP.

"If you take a cool-headed look at the balance of forces, the advantage is with the Russian side," the source added.

"News from eastern Ukraine continues to be grim," agreed Mick Ryan, a former Australian army general.

"While no major Russian operational breakthrough is expected, the Russians have been able to sustain their pressure on the Ukrainians for about a year now and it is telling".

Deep strikes into Russian territory with US-supplied ATACMS missiles could in theory disrupt or even push back Moscow's advance.

But "these missiles have already been in use for at least a year and a half" in Crimea and the Donbas, Moscow-based military analyst Alexander Khramchikhin pointed out.

"You can't launch missiles directly from the front line, because then the launchers won't last long," he added.

He suggested the US had delivered a "very limited" number of missiles and launchers to Kyiv, although no reliable estimates are available of the true figures.

In any case, the Russians "long ago moved their most critical resources out of ATACAMS' range", said Stephen Biddle, an international relations professor at New York's Columbia University.

"I don't think it's going to be decisive for the direction of the war" that Ukraine now has permission to hit Russian territory with them, he added.

ATACMS missiles can carry a payload of a single charge or cluster munitions that spread multiple small explosives over a large area, analysts at British private intelligence firm Janes told AFP.

Ukraine could use them against "deep targets such as logistics hubs that would slow resupply, or command and control nodes," they added -- although given the time Russia has had to prepare, "this might not be as great an influence as initially expected" on the front line.

Just like Western deliveries of major equipment such as heavy tanks or fighter aircraft, Kyiv has had to push relentlessly for many months to secure Washington's green light.

No individual weapons system alone will be enough to turn the conflict in one side's favour.

Fast-moving, highly manoeuverable ATACMS missiles are "difficult targets to intercept" but "the Russian S-400 air defence system offers an ability to counter tactical ballistic missiles," the Janes' analysts noted.

Several experts suggested that rather than handing Kyiv a decisive weapon, Biden's decision is aimed at influencing both domestic and international policy towards Ukraine -- which faces being forced into talks on unfavourable terms as support from the West flags.

Within the US, Trump will take over the presidency in two months and could reverse Biden's move.

"The administration wants to push all of the aid that has currently been authorised by the Congress into Ukraine, before January 20th," Biddle said.

After then, any commitment from Biden "doesn't constrain the Trump administration in any way".

On the global stage, the missile authorisation marks a counter-move to the deployment of North Korean reinforcements to Russia's front line.

Biden's team "wants Putin and... the North Koreans to understand that there are costs to escalation," Biddle said.

"I worry that the administration's emphasis on the missile issue has been too much on 'sending a message' to China and North Korea and not on delivering a consequential upgrade to Ukraine's strike capability," said Ivan Klyszcz of the Estonia-based International Centre for Defence and Security (ICDS).

"Will Washington allow Kyiv to aim for targets inside Russia that are not connected to north Korea?... This point remains ambiguous to me," he added.

"Some have argued that the authorisation could be a bargaining chip in negotiations" between Russia and the US, Klyszcz noted -- although "Trump remains as unpredictable as usual".