A Taiwanese American nuclear engineer pleaded guilty Friday to one count of conspiring to produce “special nuclear material,” in this case plutonium, outside the United States without a license from the secretary of energy.

The prosecution of Szuhsiung “Allen” Ho and a colleague marks the first time the Justice ­Department has brought cases under a 1946 Cold War-era proliferation statute.

As part of the plea agreement, prosecutors will drop charges that Ho, who owns a consulting business in the field of commercial nuclear energy, intended to illegally help China and that he acted as a foreign agent. That means Ho, 66 and a naturalized citizen born in Taiwan, no longer faces a potential life sentence but a maximum of 10 years in prison.

Nuclear energy experts say they are baffled that the government pursued the case at all. They say that the government is taking an old statute meant to discourage the spread of nuclear weapons and is applying it to an export licensing matter involving commercial reactor technology used around the world — activity that had nothing to do with bombmaking.

[China ‘closely following’ Trump comments on nuclear policy]

“To make this a case about getting plutonium for bombs is a wild overstretch, and a pretty astonishing display of ­Department of Energy and State Department hypocrisy,” said ­Victor Gilinsky, a physicist and independent consultant who served two terms on the Nuclear Regulatory Commission. “We urge everybody to build reactors, and we sell reactors. All ­uranium-fueled reactors make plutonium — even commercial reactors. So if Ho is engaged in a conspiracy to produce ­bomb-usable plutonium in ­China, his co-conspirators are DOE and State — and the White House.”

But the government insists that Ho endangered national ­security.

“It’s a very serious case no matter how insignificant the defense may allude to the technology involved here,” said Charles E. Atchley Jr., an assistant U.S. attorney in the Eastern District of Tennessee, in a June hearing. “The defendant in this case is charged with procuring and helping to obtain on behalf of the Chinese government technology that it is not allowed to have.”

Ho’s case follows several prosecutions of Chinese American scientists who were accused of sharing U.S. technology secrets with China, but whose cases collapsed. Two of those cases, involving a Temple University professor and a National ­Weather Service hydrologist, were handled by defense ­attorney Peter Zeidenberg, who is also ­representing Ho.

[China has an awful safety record — and want to run 110 nuclear reactors by 2030]

Ho was accused of violating a provision of the Atomic Energy Act by helping the state-owned China General Nuclear Power Group, formerly known as the China Guangdong Nuclear Power Company (CGNPC), more quickly design and make components for nuclear reactors. Prosecutors in Knoxville say he paid a colleague, Ching Ning Guey, who worked at the Tennessee Valley Authority, to travel to China in 2013 at the power company’s request to provide nuclear consulting. They allege that Ho encouraged Guey to share reports on nuclear power generation that he got through his work at TVA.

Ho’s assistance to the ­company focused on advanced fuel assembly research and the validation of nuclear ­reactor-related computer codes, among other things — all of which he did without a license, the government says.

Attorney General Loretta E. Lynch signed off on Ho’s ­prosecution, as required by the statute.

Guey in 2015 pleaded guilty to one count of producing special nuclear material overseas ­without a license — the same charge Ho pleaded guilty to. The government agreed not to bring other charges against Guey in return for his cooperation against Ho. Guey, who unlike Ho was not jailed pending trial, has not yet been sentenced.

The Energy Department has certified that the technology that Ho shared is illegal to export to China without special ­authorization, according to the plea agreement.

“I think that fundamentally this is more about theft of trade secrets than national security,” said Edwin Lyman, a nuclear proliferation expert at the Union of Concerned Scientists. “It does appear that there was some transfer of proprietary ­information,” he said after ­reading the indictment. But, ­Lyman said, “my sense is that the U.S. government is trying to make an example out of Ho by escalating the seriousness of the alleged offenses.”

Jonathan Poling, a former ­federal prosecutor who handled export control cases, said it is difficult to say whether Ho’s case is entirely commercial in nature or whether there were national security issues linked to entities or acts not discussed in the indictment. He said that “could be precisely why the government charged the case,” to protect the Energy Department’s and ­national security agencies’ “ability to make this assessment from the outset.”

China, which tested its first nuclear bomb in 1964, has about 260 warheads and the material to make more. Its main priority has been expanding its commercial nuclear power, with about two dozen reactors under construction. The Obama administration, with the passive approval of Congress, renewed a nuclear cooperation agreement that does not prohibit China from buying reprocessing technology that would help it produce weapons-grade plutonium from spent nuclear power plant fuel of U.S. origin.

Ho, who used to work for Westinghouse Electric Co., argued that he went to China not to produce plutonium to make a bomb but rather to help commercial nuclear power plants operate safely.

He has said that he sought guidance on whether he needed a license from the Energy Department and received equivocal responses. He said he was told that a license was not needed for his information technology work, but that he might need one for consulting on safety-

related issues. He applied for a license for the latter, but months went by without a response. During that time he continued to consult, under the apparent belief that he was permitted to do so, according to the court record.

The Energy Department declined to comment.

Ho’s defense team noted that in 2005, the government approved Westinghouse’s sale to China of $10 billion worth of the AP1000, one of the most advanced commercial nuclear power reactors in the world. Westinghouse, now owned by Japan’s Toshiba, was permitted to share all the associated technology as well as almost 600 tons of enriched uranium as fuel. It makes no sense that Westinghouse could sell such an advanced nuclear reactor to China, but that Ho could be punished with life in prison for advising a Chinese company on how to safely operate a less advanced plant, Ho’s defense team argued.

Ho’s detention, which entails lockdown 23 hours every day, has been arduous and unnecessary, his defense team has argued. Ho has been willing to post his home and those of a relative and a friend as bail, wear an ankle monitor, give up his passport and pay for security guards to monitor him around the clock. But the government has said he is a flight risk, and an appeals court has ruled he should remain in jail.

This story has been updated to describe Ho as a Taiwanese American not Chinese American.