Americans and travelers who are planning to see the Times Square ball drop in person on New Year's Eve will be surrounded by heightened security measures in the hours ahead of and after ringing in 2024, according to New York Gov. Kathy Hochul. New York State Police will ramp up staffing and state troopers, and the New York National Guard and other agencies will join in to patrol some areas.

The move comes after the Federal Bureau of Investigation and other federal agencies warned police departments across the country about potential threats to large crowds celebrating the holiday, including from lone actors motivated by the Israel-Hamas war.

Public safety agencies are increasing security across the nation ahead of New Year's Eve celebrations following the FBI alert. In Las Vegas, where hundreds of thousands of people are expected to gather to celebrate the holiday, for example, police said they are heightening security by mobilizing a bomb squad and hazmat teams and using low-level helicopter flights.

In New York City, Mayor Eric Adams said the city has not received any credible threats but is acting "out of an abundance of caution."

"Safeguarding events — of any size — is something we do better than any other city in the nation," Adams wrote on X. "But, out of an abundance of caution, you'll see a large security presence on the ground and in the air during the festivities to ensure New Yorkers can celebrate safely."

What security threats are federal authorities worried about?

The FBI, Department of Homeland Security and National Counterterrorism Center cautioned police agencies and the American public in their alert earlier this month about potential safety threats during New Year's Eve gatherings. They cited "ongoing tension between Israel and Hamas" and an increase in hate crimes across the nation as grounds for the warning.

Authorities are specifically worried about violence in large crowds.

"Lone actors may seek to disrupt or escalate violence at large gatherings, high profile events, or symbolic or religious locations throughout the winter. Such gatherings could become a convenient target for those inspired to commit violence against Jewish, Christian, Muslim, and Arab communities," the FBI said in its advisory.

"Although this announcement is not in response to any specific plotting activity, these targets likely remain attractive to lone actors inspired by a range of ideologies due to their accessibility and symbolic nature," the agency said.

FBI official Robert Kissane told CNN that "we're in a heightened threat environment," and have been since Oct. 7 when the war between Israel and Hamas started.

The agency is encouraging people to report any suspicions or potentials to public safety.

"We take all potential threats seriously and will work closely with our law enforcement partners to determine their credibility, share information, and take appropriate investigative action," the advisory said.

Cities across the U.S., world beef up security for New Years Eve

A threat assessment obtained by ABC News said New Year’s Eve in San Francisco “remains an attractive target for foreign terrorist organizations, homegrown violent extremists, and domestic violent extremists" as well as lone offenders.

The FBI's San Francisco office told USA TODAY the document had been “leaked” and declined to provide a copy. The agency sent a statement explaining that such assessments are regularly conducted to coordinate and address potential threats. 

"We encourage the public to remain vigilant and report suspicious behavior to law enforcement immediately," the office said.

ABC reported the document indicates high-profile events with big crowds and media coverage like the New Year's Eve celebration could be an area of concern, but no specific threats had been reported.

Robert Rueca, a spokesperson for the San Francisco Police Department told USA TODAY it will have a “large presence” of officers where celebrations are expected, along with staffing at district stations. Rueca said the department is not aware of any credible or specific threats to the city.

Las Vegas police anticipate nearly 400,000 people on the Strip for New Year’s Eve celebrations. Even though there are no credible threats, Las Vegas Metropolitan Police Undersheriff Andrew Walsh said authorities aren't taking any chances.

Boston city officials said law enforcement will be present “in abundance” for the city's New Year’s Eve activities, including First Night Boston. The event is expected to attract more than 200,000 visitors for its fireworks, carousel rides, improv shows and other activities.

Security concerns for New Year's Eve celebrations beyond the US.

France is deploying 90,000 law enforcement officers on New Year’s Eve, domestic intelligence chief Céline Berthon said, including 6,000 in Paris where more than 1.5 million people are expected for celebrations on the Champs-Elysees.

French Interior Minister Gerald Darmanin said at a press conference there is a “very high terrorist threat” because, in part, of “what is happening in Israel and Palestine,” referring to the Israel-Hamas war. Police will be able to use drones as part of security work for the first time, and tens of thousands of firefighters and 5,000 soldiers will also be deployed, he said.

Contributors: Rene Ray De La Cruz, Victorville Daily Press; Associated Press

Contact Kayla Jimenez at [email protected]. Follow her on X, formerly Twitter, at @kaylajjimenez.