Russia now has more than an estimated half a million troops ready to move into Ukraine, analysts have revealed, just days after Putin’s army crashed through the border into North-East Ukraine.
In comparison, Ukraine’s entire active ground forces comprise roughly 250,000 personnel.
The newly-increased size difference has prompted concerns from experts, and comes as the Western ally waits with bated breath for the first deliveries of a long-delayed US military assistance package worth tens of billions of dollars.
Dr Jack Watling, from the Royal United Services Institute (RUSI), said: "The Russian forces have now expanded to 510,000 troops.
"The outlook for Ukraine is bleak. Its allies must replenish stockpiles."
Dr Watling’s call for an assistance drive from Ukraine’s partners echoes comments by senior Western defence figures, many of whom have pledged unequivocal support for the embattled country in the months and years ahead.
In the UK, ministers have hailed a number of defence spending measures - both domestic and on Ukraine - not least, a multi-billion-pound defence boost announced by Rishi Sunak earlier this year.
In the EU - which has handed Ukraine €32billion (£27billion) since Russia's February 2022 invasion - officials have been working on a new security agreement due to signal support for the country in the event of "future aggression".
MORE ON RUSSIA-UKRAINE:
The bloc's foreign affairs spokesperson Peter Stano saying the commitments would "help Ukraine defend itself in the long term, deter acts of aggression and resist destabilisation efforts".
While in the US, senior figures in the Biden administration travelled to Kyiv mere days ago to reassure President Volodymyr Zelensky that American help was "on its way".
The country's Secretary of State Antony Blinken, part of the delegation in Ukraine, said: "We know this is a challenging time.
"But US aid is going to make a real difference against the ongoing Russian aggression on the battlefield."
The package, passed in Congress just over a month ago, ring-fences $61billion of military assistance which could prove decisive as the war churns on.
And the bill isn't the only financial care package from US; the military behemoth is preparing a $400million military aid package for Ukraine, as it returns to a regular pace of supplying weapons to Kyiv.
The news will buoy Ukrainian prospects though, as Putin’s forces storm closer to the country’s second city Kharkiv, army bosses have raised fears that reserves are running out entirely.
General Kyrylo Budanov, in charge of Ukraine's military intelligence, said: "I've used everything we have... Unfortunately, we don’t have anyone else in the reserves."