The US has pledged $756 million in humanitarian assistance to the Syrian people, US ambassador Linda Thomas-Greenfield told the UN Security Council.
The extra funding will help partners “provide clean water, food, hygiene and relief supplies, shelter, protection services, and critical health and nutrition assistance", read a statement from the US mission.
The announcement comes amid a cholera outbreak that has killed at least seven and the UN fears it could spread from Aleppo in the north to all 14 provinces.
About 13 million Syrians, which is more than half of the country’s population, are currently displaced.
Of those, 6.8 million have fled beyond the country’s borders and are now refugees.
According to the UN, the civil war, which has ravaged the country for more than a decade, is at risk of flaring up again.
"Syria cannot afford a return to larger-scale fighting, but that is where it may be heading," said Paulo Sergio Pinheiro, chair of the UN's Syria commission.
The US announced in May it would send $800m to Syria to “supporting the future of Syria and the region".
Since the start of the Syrian civil war 11 years ago, the US government has been the single biggest donor of humanitarian aid providing over $15 billion in assistance.
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Reuters contributed to this report