Martin Dempsey, the chairman of the Joint Chiefs of Staff who led US troops in Iraq during the 2003-2011 occupation, urged member states to step up their support for UN peacekeeping.
It marked the first time that the head of the US military went to New York to meet UN member states to discuss the world body's peacekeeping efforts, a US diplomat said.
Dempsey urged member states to make greater contributions to mitigate "significant equipment shortfalls" and to commit to rapid response forces for emerging crises.
"A stitch in time saves nine," he told the audience of ambassadors and military advisers at the 69th Regiment Armory.
"The rapid deployment of units within 30, 60 or 90 days -- for a finite period -- can help resolve developing crises, prevent expanded conflict and in the process save more innocent lives."
The United Nations currently runs 16 peacekeeping missions, staffed by more than 126,000 personnel and operated under an approved budget of more than $7 billion.
Dempsey called for more highly skilled uniformed personnel to staff future missions and improve operations on the ground.
"The complex array of threats and... geopolitical jockeying requires all of us to contend with an unpredictable landscape," he said.
"Our support to peacekeeping operations must keep pace."
His speech underlines growing US interest in UN peacekeeping and comes ahead of a summit on peacekeeping that President Barack Obama will host in New York in September.
UN peacekeeping missions are increasingly under threat and asked to manage, rather than resolve conflicts, but have been rocked by a series of embarrassing sexual abuse scandals.
Last year, the number of people forced from home by violence rose to nearly 60 million, which Dempsey called "a direct consequences of proxy wars" that are "difficult to contain."
"The resulting humanitarian catastrophes fuel further instability and state fragility. It's a terrible cycle, in which we find ourselves," he said.
"Member states must make greater efforts to pool our resources, our capabilities and our thinking."
The United States finances around 28 per cent of the total UN peacekeeping budget and has 80 police, military experts and troops in peacekeeping missions, according to the UN website.
Dempsey is due to step down from his post later this year.
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