World leaders are gearing up to confront grim life or death challenges this week at the United Nations, seeking ways to halt jihadist militants in Iraq and Syria and stem the spread of Ebola.
More than 140 heads of states and governments are converging on New York for the annual UN General Assembly, as crises on many fronts put multilateralism back in fashion.
"There is plenty of reason to be uneasy over the state of the world. But there is also plenty of reason for hope," UN Secretary General Ban Ki-moon said ahead of the gathering.
US President Barack Obama will be among the first to speak at the when debate swings into gear on Wednesday, with the jihadist advance in Iraq and Syria the dominant theme.
During a string of bilateral meetings, the United States will seek to shore up an international coalition to confront the threat from the Islamist State group that controls a large swath of Iraq and Syria.
On Wednesday, Obama will chair a UN Security Council meeting on stemming the flow of foreign fighters to Syria and Iraq, pushing a resolution asking countries to make it a crime to join the jihad.
Leaders will also seek to pool efforts to combat Ebola, which the Security Council has declared a threat to world peace, to rebuild Gaza after a devastating 50-day war and to encourage an end to fighting in Ukraine.
Turmoil in Libya and in Yemen is also on the agenda, as well as the new United Nations peace push in Syria, where envoy Steffan de Mistura is trying to jumpstart negotiations.
Among the headliners at this year's assembly will be India's Prime Minister Narendra Modi who will be making his maiden speech, but attention will also turn to President Hassan Rouhani of Iran.
At last year's gathering, Rouhani held a historic phone call with Obama, their first direct talks since the 1979 Revolution, but no such contact is expected this time around.
Top negotiators from Iran and six powers -- Britain, China, France, Germany, Russia the US -- are meeting on the sidelines to seek progress towards a deal to curb Tehran's nuclear program.
In his address on Friday, Palestinian leader Mahmud Abbas is expected to outline his vision for Middle East peace after demanding the UN set a date for the end of Israeli occupation.
Israel's rebuttal is sure to come from Prime Minister Benjamin Netanyahu during his speech on September 27.
Ahead of the General Assembly, about 120 world leaders will attend a UN climate summit on Tuesday, aimed at injecting momentum into upcoming climate change talks.
- Celebrities and no-shows -Ban will be joined by Hollywood celebrity Leonardo DiCaprio at the climate summit.
Spice Girl-turned-fashion-designer Victoria Beckham comes to the UN on Thursday to discuss AIDS awareness.
And actress Emma Watson of "Harry Potter" film fame helped kick off a campaign on gender equality at the weekend.
Russian President Vladimir Putin will stay away from the diplomatic marathon but North Korea is sending Foreign Minister Ri Su-yong, the highest-level Pyongyang official to attend in 15 years.
The Ebola crisis is high on the agenda, with Ban gathering top ministers on Thursday to rev up urgent aid to West Africa, where health systems are overwhelmed by the outbreak.
The United Nations is seeking to raise nearly $1 billion to defeat the worst-ever outbreak of Ebola, which is on track to infect 20,000 people by the end of the year.
The General Assembly debate wraps up September 30.