WASHINGTON — The U.S. Justice Department, which successfully prosecuted ITT Corp. for letting China get data on night-vision goggles, is planning to bring more cases against weapons brokers and companies that violate export laws.

“We want to see more investigations,” Kenneth Wainstein, head of the department’s National Security Division, said in an interview. “The more involvement, the more effort we can put into it, the better.”

Justice Department officials regard the initiative as part of the war against terrorism , though not all thefts are tied to terrorist groups. About 108 countries tried to obtain protected or sensitive American technology in 2005, which “imposed huge costs” on the economy, according to a study last year by the Office of the Director of National Intelligence.

Prosecutors are targeting illegal transfer of such products as assault rifles , missile parts, and medical devices that can be made into nuclear triggers. The agency assigned veteran prosecutor Steven Pelak in Washington to oversee investigations and train lawyers to meet a growing caseload.

Technology thefts are “going on in spades,” said Mr. Pelak, an 18-year prosecutor who last month was appointed the Justice Department’s first national export control coordinator .

The Justice Department prosecutes companies that willfully violate the law. In the ITT case, the White Plains, N.Y.-based defense contractor pleaded guilty to two criminal charges in March and agreed to pay $100 million in penalties for exporting weapons-grade night-vision technology to China. Prosecutors said ITT was trying to cut costs by shipping technology and components without export licenses to a Singapore company that did business in China.

While the government remains committed to prosecuting wayward corporations, it prefers that companies report any violations they discover, Mr. Pelak, 47, said in an interview.

“It’s not in their economic interest to be involved in a grand jury investigation,” said Mr. Pelak. “It’s hugely expensive.” Voluntary disclosures “really do make a difference,” he said.

In one continuing case, an optoelectronics unit of Waltham, Massachusetts-based PerkinElmer Inc. collaborated with agents from the Commerce and Homeland Security Departments to catch arms dealer Asher Karni, who was shipping triggered spark gaps to Pakistan via South Africa. The devices are high-speed electrical switches used to help treat kidney stones but can also serve as a detonator for nuclear weapons.

The company’s help, Pelak said, led to the arrest and 2005 guilty plea of Mr. Karni. A Pakistani businessman charged in the case, Humayun Khan, is a fugitive.

The Justice Department crackdown is driven by concern that terrorists are behind the espionage. Within the past year, the agency has targeted attempts to send surface-to-air missiles and machine guns to the Tamil Tigers terror group in Sri Lanka, sniper rifles to Indonesia and military combat simulation software to China, Malaysia, and Thailand. “Any proliferation now has potential terrorism implications,” said Mr. Wainstein.

Attorney General Gonzales emphasized the initiative in a speech last month, saying the department is using lessons it learned after the September 11 attacks to better coordinate probes.

“We know there is a substantial demand by terrorists and rogue regimes for restricted U.S. technology, including nuclear weapons components,” Mr. Gonzales said.

Mr. Gonzales told a conference in Miami last month that prosecutors are looking for novel ways to catch companies and people who break the export laws, focusing on “prevention rather than reaction.”

Like the war on terror, which exposed gaps between intelligence and law-enforcement agents, the government’s handling of export cases has been criticized for poor cooperation between federal agencies. The cases can involve five Cabinet-level departments — Defense, Justice, State, Homeland Security, and Commerce — which don’t always communicate well.