A string of jihadist attacks and rising risks to the global economy overshadowed Wednesday's opening of the annual meeting of the world's rich and powerful in a snow-blanketed Swiss ski resort.
The Taliban assault on a university in Pakistan that left at least 21 dead was a jolt to the billionaires, business titans and leaders gathering in Davos that include Pakistani Prime Minister Nawaz Sharif.
The heightened security threat was starkly in evidence in Davos itself, with police carrying machine-guns patrolling the streets and concrete blast blocks placed in front of key venues.
Even as Hollywood star Leonardo DiCaprio was helping get events under way Tuesday, the International Monetary Fund (IMF) sounded the alarm about perils in the major emerging economies and lowered its outlook for global economic growth this year.
The slowdown in Chinese growth is especially darkening the mood of policymakers in Davos after Beijing announced that GDP grew at its slowest in a quarter of a century last year.
"The big event that I think has captured everyone's attention is the developments in China and in particular the fact that growth is slowing," IHS chief economist Nariman Behravesh told AFP.
The Chinese policymakers have "fumbled", he said. "They have made some mistakes. And they have added to the uncertainty and the volatility by their behaviour."
China's problems will be discussed by the Davos delegates -- "but they won't say it in public, they will say it in the hallways," Behravesh said, noting that "the public Davos is a little different than the private Davos."
That is exactly why 2,500 movers and shakers make their annual pilgrimage here -- to air the biggest issues openly and, when they wish, far from the prying eyes of their domestic audiences.
For example, the foreign ministers of two countries deep in conflict -- Saudi Arabia and Iran -- are attending, although a public meeting is considered unlikely.
- Migrant furore in focus -
US Vice President Joe Biden is expected to be the key speaker on Wednesday, laying out his vision of the turbulent times that the global economy is facing.
Europe's migrant crisis is the other theme running through this year's Davos.
German Vice Chancellor Sigmar Gabriel and Swedish Prime Minister Stefan Lofven take part in a debate Wednesday on how to integrate migrants, at a time when the fallout from the New Year's Eve sex attacks in Cologne threaten Germany's open-armed approach to admitting hundreds of thousands of people.
Later in the week, leftist Greek Prime Minister Alexis Tsipras locks horns once again with his bete noire, German Finance Minister Wolfgang Schaeuble.
On Thursday, Argentine President Mauricio Macri will make his first appearance at Davos since his election in November, setting out his case for economic reform in a country with a turbulent recent past.
Also on Thursday, Nigerian President Muhammadu Buhari is expected to face questions about his handling of the Boko Haram insurgency in Africa's most populous country.
Oscar contender DiCaprio, a long-time environmental campaigner, used his appearance to urge leaders to make good on commitments they made at last year's UN climate talks in Paris to limit global warming and curb the use of resources such as coal.
"Our planet cannot be saved unless we leave fossil fuels in the ground where they belong. Twenty years ago we described this problem as an addiction, today we possess the means to end this reliance," he said.