Seismic is an overused word. Not when it comes to events currently under way in Syria, a country straddling the fault lines of the Middle East.
The collapse of the Assad regime, if it comes, will be the most significant event yet in the upheaval that’s followed the 7 October attacks by Hamas in Israel last year.
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It would be the end of a brutal reign of terror that has lasted since the Assad family under patriarch Hafez Assad seized power in the early 1970s. And the end of a devastating civil war that has raged since 2011.
The Assads have maintained their grip on Syria with diabolical cynicism. They have used massacre and torture, chemical weapons and barrel bombs, to secure their rule for almost five decades.
But they have also cleverly leveraged their country’s pivotal position to secure support from willing allies.
Iran has backed the regime in return for help propping up Tehran’s axis of terror across the Middle East. Syria has been used as a base for Iranian troops and a conduit for arms supplies to Hezbollah.
President Bashar al Assad has given Moscow a Mediterranean sea port and an air base nearby in return for Russia’s military support against his enemies.
The likely demise of Mr Assad and his murderous family will therefore change utterly the power dynamics of this troubled, volatile region.
Hezbollah already much reduced by Israel in recent months, will lose a key patron. Iran’s strategy of menacing Israel with proxies will have collapsed. And Russia may be forced to end its Levantine project too.
Given President Vladimir Putin’s investment in the region in men and money, that will be a bitter blow with serious implications for the Russian leader’s prestige.
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What matters is what follows. The rebel group, Hayat Tahrir al Sham (HTS), appears to have evolved from its al Qaeda- inspired roots. As well as dramatically improving its fighting ability, it has displayed a tolerance for different religions and surprising discipline.
But these are early days. It is not clear who is supporting the rebels and what they intend to do with their victory.
But every revolution since the Arab Spring has unravelled into chaos and bloody disorder.
If the same happens in Syria, the ramifications for the Middle East could be grave given its pivotal position in a region wracked with conflict and division.