Where will the world’s next catastrophic war erupt? And what will trigger it?
However risky the North Korean nuclear stalemate remains, the more likely battleground once again appears to be the Middle East.
And the growing rivalry between the region’s most powerful countries — Iran and Saudi Arabia — will be what triggers it.
In recent weeks, the potential flashpoints across the Middle East have been dangerously intersecting with each other.
They include the deepening war in Syria, the risk of Israeli involvement, the humanitarian disaster in Yemen, the disarray within Lebanon, the continuing sectarian conflict in Iraq and the fear that new nuclear weapons may be introduced in the region.
But magnifying the risk is what looms above all these conflicts.
In varying degrees, all are being fuelled or influenced — as a form of proxy war — by what many Middle East analysts fear is the coming showdown between Iran and Saudi Arabia.
This is not only a showdown over religion, dividing all of Islam, with Shia Iran and Sunni Saudi Arabia at the opposite ends of an Islamic rift that dates to the 7th century.
Above all, it is a showdown about power and history in the Middle East. Who will dominate the region? Who will shape the future? And who will lose?