When Syria's long-time staunchest ally Russia says so, it's time to sit up and take notice.
"Losing control" was how Russia's DeputyForeign Minister, Mikhail Bogdanov, summed it up yesterday in a statement bound to be taken in Damascus as something of a stab in the back.
For Mr Assad, the timing of Moscow's negative assessment could not have come at a worse moment, as almost daily now, Syrian opposition fighters gain substantial battlefield momentum.
One can't help wondering how many Syrians loyal to the Assad regime will now be tempted to shift their loyalties and throw in their lot with the opposition after hearing Mr Bogdanov's remarks.
If that should happen, then events on the ground will most likely take on a new volatility and present an even more urgent need for the international community to address some testing and complex security issues arising from the Syrian conflict and its fallout.
Before taking a closer look at those issues, however, it's worth pausing to take note of other tell-tale signs that indicate the beginning of the end for Mr Assad.
A useful starting point is last month, with what was initially thought to be the defection of Jihad Makdissi, a senior foreign ministry spokesman and one of the highest-ranking Christians in the Syrian regime.
Since Mr Makdissi's departure from Syria there has been growing speculation among intelligence analysts that far from being a defection, his leaving was in fact facilitated by the regime and that he is on a diplomatic mission to negotiate a safe exit and possible exile for the Assad Alawite clan, and guarantee the security of other Syrian minorities like his own Christian community in a post-regime Syria.
Another indicator of the regime's collapse – if US and Nato reports are fully corroborated – is that over the past few days the Syrian military fired six Scud missiles from Damascus towards rebel forces in the north.
Should this prove to be accurate, it is clearly a sign of desperation and a signal the air superiority the regime has depended upon until recently has quickly diminished as opposition fighters are supplied with increasingly sophisticated firepower. Over recent weeks I have been struck by news photographs emerging from Syria of opposition fighters on the streets, many of whom now seem to be carrying brand new M4 carbine rifles, a weapon heavily used by the US military.
Many of these rifles are fitted with telescopic sights useful in street sniper battles of the kind that have become the hallmark of Syrian's urban warfare and look to have come straight from their manufacturer's greaseproof wrapping.
It's small details like this that tell us not only that the regime is struggling but the opposition is militarily gaining an edge that yesterday led Nato Secretary-General Anders Fogh Rasmussen to conclude the regime's collapse is "only a matter of time".
Indisputably, this conflict has changed significantly since it began nearly two years ago. While the opposition initially operated with meagre resources and equipment, they are now bolstered by defections and outside support and have made gains on what was previously a far superior enemy.
Day in day out now, the regime's military superiority in equipment is fast eroding as opposition fighters start to utilise captured tanks, armoured personnel vehicles, artillery and especially what is known as Manpads, a shoulder-held heat-seeking missile launcher that has resulted in the downing of Syrian air force planes and attack helicopters.
What then of those most pressing wider issues for the international community I mentioned earlier that will accompany this run-up to the Assad regime's final throes? Two concerns above all will doubtless be given priority.
The first is securing Syria's substantial chemical weapons arsenal. The second – inextricably connected – issue is ensuring jihadist elements within the opposition fighters' ranks are prevented from wielding a disproportionate military and political influence in the chaos that will likely ensue as the regime crumbles.
Unlike Iraq's phantom weapons of mass destruction (WMDs) that evidently didn't exist by the time the US and Britain went to war there, Syria is known to have a large chemical weapons programme which is thought to include sarin, VX, tabun and mustard gas.
Earlier this month intelligence reports emerged that said the Syrian military has loaded the precursor chemicals for deadly sarin nerve gas into aerial munitions. While these munitions have yet to be loaded on to Syrian military aircraft, ongoing international intelligence, surveillance and reconnaissance will be vital to keep close tabs on the precise whereabouts of these stockpiles. Should their security be compromised it would almost certainly guarantee a foreign military intervention despite the West's reluctance to become deeply involved in the Syrian debacle.
Allied to this chemical weapons concern is the second most pressing issue for the international community: neutering the influence of jihadist groups currently involved in fighting the regime who would almost certainly turn their attention to undermining any Western attempts to shape a post-Assad Syria. Washington's declaration earlier this month that it would blacklist Islamist extremist opposition group Jabhat al Nusra as a foreign terrorist organisation and the backlash that resulted is a sure sign of the enormous obstacles to be overcome in coping with the jihadist threat. Not only did many other mainstream opposition groups criticise Washington's move, insisting Jabhat al Nusra's contribution is needed in the ongoing fight against Mr Assad's forces, but as many as 29 other Islamist and Salafist groups stood in solidarity with the group against the US blacklist. It's a measure of the problem the US and other countries face should the Islamists' grip extend after Mr Assad's departure.
Over the last few years ordinary Syrians have endured some terrible hardships and dangers. But as Mr Assad looks to make his last stand, a whole new raft of threats is emerging for both Syrians and the international community alike. The more that is done right now to establish a dialogue with Syrian opposition figures who are reasonable and realistic about the country's future, the less chance there is of extremists taking root.
Doing so while treading the tightrope of securing Syria's chemical weapons arsenal and avoiding, or minimising, direct western intervention is a daunting task to say the least.