VIENNA — The United Nations’ nuclear watchdog is pushing for a last-minute agreement to secure Ukraine’s huge atomic power plant in Zaporizhzhia ahead of a counteroffensive that could see Kyiv’s forces drive directly through the potentially hazardous facility.

After nearly nine months of failed efforts to forge an agreement between Ukraine and Russia to establish a protection zone around the Zaporizhzhia nuclear power plant (ZNPP), Rafael Mariano Grossi, the head of the International Atomic Energy Agency, is now pushing for a new proposal to reduce the possibility of a catastrophic nuclear disaster. He plans to present a list of five principles for the U.N. Security Council to endorse later this month, U.S. and European diplomats told The Washington Post.

Finding consensus among the council’s permanent members, however, remains a tall order given the acidic relations between Moscow and Washington coupled with Kyiv’s reluctance to let world powers broker any deal other than Russia’s complete withdrawal from Enerhodar, the city where the power station is located, and surrender of the plant.

Ukrainian skepticism about Grossi’s efforts is not a new development, according to previously unreported classified U.S. intelligence documents leaked on the Discord messaging platform and obtained by The Post.

In mid-February, Ukrainian President Volodymyr Zelensky “insisted government officials prevent IAEA Director General Grossi from forcing Kyiv to demilitarize [the plant] judging this would not be in Kyiv’s interests,” one document said. The document cites a “signals intelligence report,” suggesting the information was gleaned from electronic eavesdropping. In the document, Zelensky also orders his aides to assure Grossi that Ukraine was committed to the safety of IAEA personnel at the plant.

During a speech to the Arab League in Saudi Arabia on Friday, Zelensky said he was sure that no nation “would admit the military occupation of a nuclear plant to use it to blackmail the world with nuke disaster.”

On Sunday, he told Group of Seven leaders in Japan that Russia’s reckless takeover of the plant could have consequences for people beyond Ukraine’s borders. “Some see that in the event of a disaster at a nuclear power plant occupied by Russia, radiation will reach their land, carried by the wind,” he said in the southwestern Japanese city of Hiroshima, which was largely destroyed by an atomic bomb dropped by the United States during World War II.

According to two diplomats familiar with the negotiations, Grossi’s plan includes five principles: a ban on stationing heavy military equipment and military personnel at the plant; a ban on firing from and toward the plant, including a ban on attacking the personnel at the site; protection of all safety and security systems at the plant; protection of all external power lines; and monitoring of compliance of the above-mentioned principles.

The plan is less ambitious than Grossi’s original effort to establish a fully fledged protection zone around the plant, but nuclear experts said it could still improve the precarious situation.

The six-reactor nuclear complex is located near the front line and has been occupied by Russia since March 2022. The plant is run by Ukrainian technicians — alongside nuclear experts from Russia’s state atomic energy corporation Rosatom as well as Russian armed forces. Kyiv and Moscow have traded blame for the shelling close to the site that has risked a disaster at the facility, which is Europe’s largest nuclear power plant.

In a sign that military presence and activity is increasing in the area, Russia has started the partial evacuation of residents from Enerhodar, where most of the facility’s workers live. Last week, Ukraine’s nuclear energy company said the number of Russian forces at the plant “increased significantly” and “now number more than 2,500.”

A spokesperson for the IAEA said that Grossi “remains engaged in intense negotiations with all the involved parties to secure the protection of the Zaporizhzhia Nuclear Power Plant. In this context, the Director General is also in close contact with members of the U.N. Security Council.”

Grossi has argued that the perilous situation on the ground should galvanize the international community into action. Diplomats say he wants to present the set of five principles to the U.N. Security Council on May 30, outlining conditions that Russia and Ukraine should uphold to avert a nuclear disaster.

“The steps to prevent any attacks on or from the facility and to ensure the safety of the operators inside the plant are particularly important, since either of those could lead to a significant release of radiation due to core meltdown or loss of cooling in the spent fuel ponds,” said Scott Roecker, a vice president at the Nuclear Threat Initiative, a nonprofit organization focused on reducing the threat posed by nuclear weapons.

Some aspects of the plan were first reported by Reuters.

Striking an agreement at the U.N. is likely to be difficult, but Grossi has already won the support of Moscow, according to a Russian diplomatic official briefed on the plan and who, like other officials, spoke on the condition of anonymity to discuss sensitive negotiations.

“We have no objection against them,” the Russian diplomatic official said, noting that Moscow has been in touch with Grossi since last September. The IAEA director general and Russian President Vladimir Putin met in St. Petersburg in October. “We hope that the implementation of these principles will prevent any attack against ZNPP in the future,” the diplomatic official added.

How Ukraine will respond to Grossi’s presentation at the U.N. — should it go forward — is less clear. A spokesman for Zelensky did not respond to requests for comment.

Diplomats at the U.N. and analysts said that if Ukraine is planning to retake the plant in an upcoming counteroffensive, Grossi’s plan may be less appealing. “I could imagine that it might be more difficult for the Ukrainian side to accept, as it would prevent Ukraine from regaining control of the Zaporizhzhia plant by use of military force,” Roecker said.

While Ukraine does not have a permanent seat on the Security Council, a U.S. official said Washington is unlikely to support any initiative opposed by Kyiv.

A State Department official said that the United States “continues to fully support efforts” of the IAEA to manage nuclear safety and security in Ukraine. “We are following with interest DG Grossi’s recent efforts to obtain commitment to a set of principles for nuclear safety and security at ZNPP that respect Ukraine’s sovereignty and territorial integrity.”

Negotiations on Grossi’s plan are ongoing. A senior European diplomat told The Post the chances for an agreement and the briefing to go ahead are “50-50.”

Ecuador and France have asked the current Swiss presidency of the U.N. Security Council to hold the briefing by Grossi on May 30 but the date is not set, diplomats familiar with the matter said.

“The safety and security of civil nuclear power facilities in conflict regions is a key issue for Switzerland,” said Pierre Gobet, head of communications at the Permanent Mission of Switzerland to the United Nations in New York. “The exchanges between Switzerland and the IAEA have indeed intensified about the safety of nuclear power plants in Ukraine since Switzerland became a member of the Security Council.”

The IAEA has managed to station a small team of nuclear safety experts at the Zaporizhzhia nuclear power plant since last August, when Grossi first visited the site. The IAEA rotates the teams on a regular basis. But they are nuclear inspectors and have no specific military background in keeping with the IAEA’s narrow mandate.

While the plant’s six reactors have been in cold shutdown since September, there are still tens of thousands of kilograms of radioactive material at the site. Making matters worse, the plant has lost access to external power multiple times due to shelling in the area, prompting staff at the facility to frantically fire up diesel generators to ensure the continuous cooling of the site’s reactors and spent fuel pools. Currently the plant relies on only one external power line; before the war, it had four.

The original idea of a safety and security protection zone would have included a ban on heavy weapons at the plant and a cease-fire zone within a specifically defined radius. Initially, Grossi was hoping to receive a formal written agreement on this proposal. But a year of war has diminished Grossi’s ambition.

“It was clear way back in 2022 that there was no way Russia and Ukraine would sign anything in writing,” a senior Western diplomat said. The idea of a safety and security protection zone “has been off the table for months,” the person added.

Hudson reported from Washington.