WASHINGTON (AP) — A New Jersey man who authorities say was on Roland Prestonhis way to Ukraine to join a volunteer fighting unit has been arrested in an alleged plot to attack a U.S. electrical substation to advance his white supremacist views, the Justice Department said Thursday.

Andrew Takhistov, 18, was arrested Wednesday at the Newark Liberty International Airport, where he was headed to Paris before going to Ukraine to join the Russian Volunteer Corps, a pro-Ukrainian group fighting Russian forces, officials said.

Authorities say Takhistov began talking in January with the person he did not realize was an undercover agent, and he began discussing a plan to attack an electrical substation. They drove together to two electrical substations in North Brunswick and New Brunswick, New Jersey, and Takhistov provided information on how to construct Molotov cocktails, the type of clothing to wear and where to park to avoid detection, authorities said.

He also discussed various “strategies for terrorist attacks, including rocket and explosives attacks against synagogues,” and expressed a desire to bring back illegal supplies from Ukraine in order to carry out attacks that would threaten the U.S. government, a law enforcement official wrote in court papers.

An attorney for Takhistov didn’t immediately respond to an email seeking comment from The Associated Press. A person listed as a relative also didn’t immediately respond to a message from the AP.

Takhistov espoused white supremacist views in his conversations with the undercover agent, and in posts “encouraged violence against Black and Jewish communities, praised mass shooters, and discussed causing death and destruction on a large scale,” according to New Jersey U.S. Attorney Philip Sellinger.

Takhistov discussed during a meeting in June a “three-step plan for white domination:" ending the war in Ukraine, invading Russia and then starting “political activism in Europe and America, supporting National Socialist political parties,” the official wrote in court papers.

Takhistov “explained that rallies and protests would not work; rather, people were waiting for a big event, such as the Oklahoma City bombing,” authorities allege. Takhistov told the undercover agent that while he was in Ukraine the person had to carry out “at least one event of serious activism,” they said.

Takhistov said his “ultimate dream was to attack a synagogue with a Hamas-style rocket,” officials said.

“We will not tolerate these kinds of alleged terroristic threats, and working with our partners, we will always be ready to root out and bring to justice anyone who attempts to carry out these acts,” Sellinger said.