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Jim Cole, Associated Press
New Jersey Gov. Chris Christie, R-N.J. takes a questions during a town hall meeting with area residents in Londonderry, N.H., Wednesday, April 15, 2015.

LONDONDERRY, N.H. — New Jersey Gov. Chris Christie said Wednesday the emerging nuclear pact with Iran will lead to it having nuclear weapons and to an even more dangerous Middle East. He also said he'd be open to putting U.S. soldiers "into the fight" against the Islamic State group if necessary.

Introducing himself to New Hampshire voters in a format he knows well — a town hall-style meeting — Christie said the world has no reason to trust Iran. He said it takes guts to enter a deal, but also to back away from one— which he urged President Barack Obama to do.

The comments came in response to one of nearly 20 questions the likely 2016 Republican presidential contender answered during a 90-minute town hall event, his first in the early voting state after more than 130 at home. Christie drew a capacity crowd at the Londonderry Lions Club and fielded questions on normalized relations with Cuba — he opposes them — his stance on vaccinations, immigration, the Islamic State group and more.

His reviews from the crowd were solid. Michael Holzberger, 46, an accountant from Londonderry, said he came to the event thinking of Christie as a "typical" mild northeast Republican, "but he came across very forceful today."

"I loved the way that he answered clearly the questions," Holzberger said. "It wasn't any baloney."

Christie has often declined to discuss national issues that don't directly affect New Jersey, but he said earlier Wednesday that he'd been studying up to be part of the national conversation.

Christie said he had "grave concerns" about the preliminary deal between the U.S., Iran and five other world powers aimed at curbing Iran's nuclear ambitions. It would ultimately compel Iran to reduce the number of centrifuges used to enrich uranium and agree to inspections of its nuclear sites, among other things, in exchange for the lifting of economic sanctions.

Christie said the deal would lead the Saudis, Egyptians and Jordanians to pursue nuclear weapons, calling Iran the world's largest state sponsor of terrorism and a nation that cannot be trusted.

"They have no basis to have earned our trust," he said.

Asked about how he'd handle the threat posed by Islamic State militants, Christie accused Obama of weak leadership and said the country needs to assure its allies that the U.S. will stand beside them.

"We have to be willing as Americans to say, if need be, we'll also put soldiers into the fight," he said. "We have to be willing to say that." He did not specify in what ways he might support the deployment of U.S. forces on the ground.

Obama has ruled out ground troops for now in Iraq, where a U.S.-led coalition of Western and Arab countries has been launching airstrikes on Islamic State targets since last fall.

On improving ties with Cuba, Christie said Obama "should be ashamed of himself" for taking the U.S. in that direction. Obama recently met Cuban President Raul Castro as part of each country's cautious outreach to the other.

"If Cuba wants to normalize relations with the United States, start acting like a normal county," Christie said. "Start acting like a civilized country."

Christie has repeatedly called on Cuba to extradite Joanne Chesimard, a member of the Black Panther Party and Black Liberation Army who was convicted in 1977 of killing a New Jersey state trooper, then fled to Cuba, where she has lived ever since.

"It is a national disgrace that this president would even consider normalizing relations while they are harboring a terrorist murderer who belongs in prison in New Jersey," he said, calling the move to remove Cuba from the list of state sponsors of terrorism "insane."

The United States says the return of American fugitives is part of the ongoing discussions with Havana.

The governor, who has struggled to gain traction in the early stages of the 2016 primary campaign, appears to be ramping up his efforts. His trip has been an opportunity to showcase what backers say are his greatest assets: his ability to connect with everyday voters and answer questions off the cuff.

That Christie was on display Wednesday as he shared stories about growing up in a lively family, lessons he learned from his mother and a few casually cracked jokes.

Christie also tried to end any lingering questions about his stance on vaccinations. During a trip to Britain in February, Christie was panned after he said that parents should have "some measure of choice" when it comes to vaccinating their children. Asked Wednesday whether parents could count on him to support the right to opt out of vaccinations, Christie took a different tone.

"Ya know, you can't count on me for that," he said, adding that while parents should be heard, public health is his primary concern.

Follow Jill Colvin on Twitter at: http://twitter.com/colvinj