Authorities are stepping up security throughout New York City in the wake of the explosion Saturday night in Chelsea.

An additional 1,000 state troopers and members of the National Guard have been placed at transit hubs and other areas.

New York City Police Commissioner James O’Neill says the department has reviewed its security plan for the UN General Assembly meeting this week.

O’Nell said the NYPD is satisfied with the plan that is currently in place.

“This is what we do. We do it very well,” said O’Neill. “We’ve been doing this for years. So we took a look at our coverage, our detail for the weeks. We’re satisfied we are where we need to be.”

135 heads of state and government and more than 50 ministers will be attending the meeting at the U.N.

The spotlight during the week is certain to shine on three leaders, who are all scheduled to speak at the assembly’s opening ministerial session on Tuesday morning.

U.N. Secretary-General Ban Ki-moon who steps down on Dec. 31, and U.S. President Barack Obama who will leave office in January, will be addressing the 193-member world body for the last time. And British Prime Minister Theresa May will be making her debut on the world stage less than three months after the vote to leave the European Union.

World leaders meeting at the U.N. will be trying to make progress on two intractable problems at the top of the global agenda – the biggest refugee crisis since World War II and the Syrian conflict now in its sixth year which has claimed over 300,000 lives.

Mayor Bill de Blasio said there will be a substantial police presence in and round New York City this week, at major events, major crossroads and subway stations.

“Now, for all New Yorkers, a central message we want to give today is be vigilant,” said the mayor. “Be vigilant at this point in time. Not just because of this incident, be vigilant because we’re going into the United Nations Assembly week.”

At the direction of Gov. Andrew Cuomo, state agencies, including the Division of Homeland Security and Emergency Services, the New York State Police, National Guard, the Metropolitan Transportation Authority and the Port Authority of New York and New Jersey will remain on a heightened state of alert.

(AP)