LOS ANGELES, California (CNN) -- Three men charged with sexually exploiting Cambodian children are being brought back to the United States to face prosecution, the Justice Department announced Monday.

The men are among the first charged under an international law enforcement initiative specifically targeting Americans traveling to Cambodia for the purpose of sexually abusing children.

The initiative, Operation Twisted Traveler, is an effort by the Justice Department and U.S. Immigration and Customs Enforcement to crack down on sex tourism.

"The men charged in this investigation apparently thought they could pursue their abhorrent desires by leaving the United States to prey on children in another country, but they were sadly mistaken," U.S. Attorney Thomas P. O'Brien said in a statement.

"We are now working closer than ever with officials in other nations and concerned private parties to take every effort we can to identify and prosecute sex tourists, as well as to provide every protection we can to the world's children."

Ronald Boyajian, 49, Erik Peeters, 41, and Jack Sporich, 75, are each charged with international travel and engaging in sexual contact with minors, a charge carrying a maximum prison sentence of 30 years, according to the Justice Department.

They are slated to make their first appearances in federal court on Tuesday, the Justice Department indicated in a news release.

The defendants are charged with international travel and engaging in sexual contact with minors, a charge carrying a maximum prison sentence of 30 years for each of their alleged victims, according to the department.

They are charged under the federal Protect Act, enacted six years ago to strengthen federal laws relating to predatory crimes against children outside U.S. borders, the department added.

The three defendants were apprehended, according to Immigration and Customs officials, as a result of information provided by the human rights organization International Justice Mission and the group Action Pour les Enfants, which combats child exploitation.

All three men have been previously convicted of sex offenses in the United States, the Justice Department noted in its statement.

"These types of cases are disturbing not only because young, defenseless children were victimized in unspeakable ways but also because the defendants went to such lengths to engage in their dark activities overseas," O'Brien said at a news conference.

He highlighted the case against Peeters, who was convicted on child molestation charges in 1990.

"Our case against Mr. Peeters outlines evidence of him allegedly molesting Cambodian boys, paying them small amounts of money -- $5 to $10 -- and possibly taking digital pictures of his young victims while they were naked," O'Brien noted.

He said Peeters molested at least three boys in Cambodia over the course of several months. One of the boys was 12 years old when the abuse is said to have started.

Boyajian is said to have "engaged in sexual activity with a 10-year-old Vietnamese girl in an area outside Phnom Penh frequented by child sex tourists known as 'Kilo 11,' " the Justice Department statement said.

Sporich, according to Action Pour les Enfants investigators cited in the government's criminal complaint, repeatedly hosted three Cambodian boys at a residence outside the city of Siem Reap. The complaint states that Sporich "was known to drive his motor bike through the neighborhoods while dropping Cambodian (money) on the street in order to meet kids."

The new charges "clearly demonstrate to the Cambodian people that the United States will not tolerate this type of abuse," said Carol Rodley, the American ambassador to Cambodia.

"These cases not only signal to the Cambodian victims our commitment to justice, but they will also act as a powerful deterrent for those individuals who are contemplating traveling to Cambodia to engage in illegal sexual activity with minors."

The International Labor Organization estimates that at least 12.3 million adults and children are victims of forced labor, bonded labor and sex slavery each year.

Cambodia is one of several countries recently added to a U.S. "watch list" because of what a State Department report calls a worsening human trafficking record in that country.

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