Hello and welcome to NewsHour from the BBC World Service coming to you live from London with me, Sean Lay.

In a moment, our main story this hour, the lightning advance of Syrian opposition forces on the country's cities.

Could the Assad dynasty, which has controlled Syria for more than half a century, be approaching its end?

And in half an hour, we'll also hear from South Korea.

Thousands have gathered outside the National Assembly

demanding the removal of the country's president.

But before all that, in Syria, suppression of dissent at all the Assad's have viewed so effectively before was the catalyst for the country's civil war.

That civil war erupted in 2011 when the government brutally suppressed pro-democracy demonstrations.

Now, in recent days, first Aleppo, then hammer, have fallen, cities back

in the control of Syrian rebels. They are now outside the city of Homs in the country's centre.

If that surrenders to them, could Damascus the capital be next? And if so, how soon?

For years and apparently ever-evolving kaleidoscope of rebel groups,

some jihadists, some nationalist, other secular, even liberal, exercised power at different

places at different times. Yet the government has essentially remained in control of much of Syria

and its writ has run to most of the country's cities. It's been sustained too by the attitude

of regional powers,

preventing Syria from disintegrating, as first Iraq and then Libya appeared to have done,

has been the default position of diplomats in the Middle East and beyond.

To an extent, President Bashar al-Assad has been supported because his government was perceived

as the least worst option.

Syria is a large country bordered by Lebanon to the west, Jordan and Iraq to the southeast.

To the north is Turkey, which worried that the dissolution of Syria could embolden Kurds to dream of a

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