A spokesperson says the United Nations is assessing security in the wake of an explosion on Saturday night in New York's Chelsea district as the organisation prepares to host world leaders arriving for the General Assembly.
The US Homeland Security Department was "actively monitoring and participating in the investigations" of both the NY and New Jersey explosions, Homeland Security Secretary Jeh Johnson said.
Andrew Cuomo, as many as 1,000 additional law enforcement officers have been deployed to travel hubs throughout the city in response to the incident.
"Now for all New Yorkers, a central message we want to give today is be vigilant", he said during a news conference via FoxNews.com.
President Barack Obama, who arrived in New York City on Sunday, is scheduled to speak at the 71st session of the U.N. General Assembly on Tuesday, his final address to the chamber as the US president.
Security Ramps Up Amid UN General Assembly in NYC
Given the microscope NY is now under, travelers visiting the metropolis would be wise to heed de Blasio's advice and remain vigilant and extremely patient.
New York Mayor Bill de Blasio on Sunday vowed a "bigger than ever" police presence to protect the UN.
"The Department of Homeland Security is actively monitoring and participating in the investigations of the explosions in NY and New Jersey yesterday..."
"Be vigilant because the police need your help, and if you see anything that might be pertinent to this case, we need you to call it in", De Blasio added.
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A senior military source in Damascus told AFP that the truce would expire at 7pm (4pm GMT) Monday, if no extension was announced. No aid deliveries have yet reached the besieged rebel-held part of the northern city of Aleppo, a key point in the agreement.
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A pipe bomb also exploded Saturday in Seaside Park ahead of the race for Marines and sailors, but no one was injured. A NYPD bomb disposal robot handles an unexploded pressure cooker bomb on West 27th Street in New York City.