Hungary has announced it has no target date to submit its application for a construction permit for new reactors at the Paks nuclear power plant – a move Budapest says is aimed at minimizing any safety risks, Reuters reported.

The project is one of the biggest deals Rosatom, Russia’s state nuclear corporation, is working on as it seeks to expand the list of foreign customers building its new VVER-1200 reactor series. But the Hungarian project has faced long delays due in part to a European Union review of the project and how it is being financed.

The Kremlin has thrown its weight behind the reactor project, which will add two VVER-1200 reactors to a facility that is already running four older Soviet-built pressurize water reactors. Nearly half of Hungary’s electricity is supplied by the plant.

Vladimir Putin visited Hungary in April of 2017 to oversee the signing of the 12.5-billon-euro deal, and last September he said publically that construction on the plant would being “soon.”

But recent comments by Hungary’s prime minister, Janos Suli, cast doubt on just how soon that might be.

“If anybody were to ask me for a deadline for submitting this planning documentation, I would say we will submit it when we are convinced that it can be submitted and that it will be approved,” Suli said at a news conference, according to Reuters. “It is clear that wherever you need to meet complex safety requirements, haste always comes at a big cost.”

Suli said the required documentation would have to be reviewed by Hungary’s Atomic Energy Authority, which plans to involve about 100 experts from the International Atomic Energy Agency in the assessment of the 300,000-page document.

The panel will have 15 months to deliver a verdict.

Suli said 150 engineers were working at the Paks nuclear plant, where they are pre-screening planning documentation submitted by Rosatom.

“You can see examples of all sorts in the world: of a power plant not being built, or a plant half-finished,” Suli said, citing examples in Finland.

In that case, Rosatom is having trouble getting Finland’s notoriously harsh nuclear regulator, STUK, to sign off on a construction project for two VVER-1200 reactors near the town of Hanhikivi. That plant was to begin commercial operations in 2024, but the delay from STUK has pushed back the starting date by at least four years.

Though STUK has not released any information about the delay, Suli suggested the Finnish project was being hindered by Rosatom’s difficulties in meeting European nuclear construction requirements, Reuters said.

“We do not want to commit the same mistake,” he told the news conference, the agency reported.

Last month Hungarian officials again threw sand in the gears of the plant’s progress by saying it would seek to postpone the repayment of the $10 million loan it received from Russia to build the plant until after the new reactors had begun producing energy.