New York is stepping up anti-terrorism efforts ahead of the Republican National Convention this summer.

Anti-terrorism training is nothing new to New York's police department. The NYPD has an elite unit of officers who are trained to deal with a chemical or biological attack. But now officials are expanding that program, training 10,000 officers on how to respond to a chemical, biological or radiological attack.

The NYPD is increasing training to prevent attacks as part of massive security preparations for the Republican National Convention in August. The high-profile political gathering is expected to bring the country's top Republicans to New York for several days, including President Bush.

New York City Police Commissioner Ray Kelly says the NYPD is not taking any chances when it comes to preventing another attack.

"Our belief is that terrorists like to come back here," he said. "We've been attacked twice and there have been planned attacks here three other times. So we have to be concerned about New York being targeted."

Part of the training involves officers responding to a smoke-filled room, meant to simulate a gas attack, and a contaminated subway car. Officers will also learn how to decontaminate themselves.

The training is funded by a $12 million grant from the department of homeland security.