As millions in the U.S. prepared to ring in 2018, there had already been massive celebrations around the world. In Sydney, Australia, a huge fireworks display lit up the harbor. In Hong Kong, a spectacular array of pyrotechnics wowed spectators. And in Dubai, an amazing light show on the side of the world’s tallest building, the Burj Khalifa, welcomed the new year.

Just as there was intense security at those events and others around the world, in the U.S., law enforcement agencies had been preparing for New Year’s Eve celebrations for weeks.

With rooftop snipers, bomb-sniffing dogs and thousands of officers, the NYPD ensured a safe start to 2018 for thousands of revellers packed into a frigid Times Square.

“The idea is to have enough of a visual deterrence so people will look at this and say it’s a hard target,” said John Miller, the deputy commissioner in charge of counter-terrorism.

New York’s security plan for about 1 million expected revelers included radiation scanners and bag checks, plus multi-ton trucks and concrete barriers to guard against vehicle attacks.

This year also saw police put a special focus on security from above, with officers inside about two dozen nearby hotels ready to combat any sniper-style assault, of the kind seen in Las Vegas in October.

Police in Houston may have prevented an attack, arresting an intoxicated man with guns and ammunition inside a hotel room overlooking the city’s celebrations.

Other big cities were also on high-alert. Chicago police said they had added specialized teams with a focus on vehicle-style attacks. And for the first time, Miami conducted random security checks at its outdoor events.

In Las Vegas, three months after the deadliest mass shooting in modern U.S. history, the city’s New Year’s Eve party along the famous Strip was a top priority of the Department of Homeland Security and FBI, which were sharing personnel and intelligence.

There were no specific, credible threats against the celebrations in New York or any other big U.S. city as the clock ticked toward midnight, and the events all went on without any major security incidents.