EXCLUSIVE: Moscow and Kyiv remain locked in a years-long grinding war, but in one Ukrainian city, the fight has quieted — and soon the Russian-occupied aging population in Oleshky will be offered humanitarian relief and a way out.

Behind the localized ceasefire is an unlikely mediator: first lady Melania Trump. And her diplomatic effort in the war-torn region is not over, Fox News Digital has learned.

Trump spent weeks moderating between Russian and Ukrainian officials to hammer out a deal over the devastated city in Ukraine's Kherson region, ultimately winning the trust of both governments to serve as their "exclusive intermediary," according to a senior adviser for the first lady.

The agreement brought officials from both countries together in Belarus last week to sign off on a detailed humanitarian operation aimed at getting food, clean water, medicine and doctors into Oleshky, Ukraine, and providing safe passage out for residents who want to leave.

Fox News Digital obtained the signature pages of the agreement, signed Oct. 23 by Russia's human rights commissioner, Tatyana Moskalkova, and her Ukrainian counterpart, Dmytro Lubinets. The documents also lay out plans for continued humanitarian operations in the region coordinated with the first lady.

For the Slovenia-born first lady, the war in her native Europe was not entirely unfamiliar territory: she had already mediated exchanges of Ukrainian and Russian children. Negotiating an agreement to stop the fighting, however, marked a significant expansion of that role.

Just across the Dnipro from the Ukrainian-held city of Kherson, Oleshky was once home to roughly 24,000 people. Russia seized the city at the outset of its 2022 invasion, and years of occupation and fighting have reduced its population to around 2,000, many of them elderly. The city now sits squarely on the front line.

Russian forces use Oleshky as a base for attacks across the river into Kherson, while Ukrainian forces target Russian positions in and around the city. Roads have been mined, food and medicine have become scarce and basic services have largely collapsed.

"It's hell there," Yuri Sobolevsky, deputy chairman of the Kherson regional council, told The New York Times. "People need to be evacuated from there, 1,000%. They're living 24/7 under risk of death." For Ukraine, the humanitarian mission presents a difficult tradeoff. The civilians trapped in Oleshky are Ukrainians in desperate need of food, medicine and a safe route out. But the city remains under Russian occupation and sits on an active front line, meaning halting attacks long enough to reach them also means temporarily easing military pressure on Russian forces operating in the area.

Getting Russia and Ukraine to stop firing at each other has proven extraordinarily difficult — not just for the first lady, but for her husband and his administration, which has spent much of President Donald Trump's second term trying to bring the war to an end. In Oleshky, however, both sides found a narrow point of agreement.

Oleshky first came onto Trump's radar during United Nations General Assembly week in September, when the city's worsening humanitarian crisis was raised at a Fostering the Future Together event that she hosted.

By then, the first lady had already worked with both governments to reunify 34 Ukrainian and Russian children with their families across six separate efforts, according to her exclusive senior adviser Marc Beckman, building relationships she was able to leverage when she turned her attention to Oleshky.

"The first lady's relationship with both Russia and Ukraine has been, over time, substantial," Beckman told Fox News Digital. "There's a lot of trust, and there's been a lot of success." Her team first approached Ukraine and asked whether Kyiv would authorize Trump to serve as its "exclusive intermediary" with Russia. Ukraine agreed in a formal letter, Beckman said. Trump's team then approached Moscow, and Putin responded with a letter granting her the same role on Russia's behalf.

From there, Trump began negotiating with the highest levels of government in Russia and Ukraine, with both Russian President Vladimir Putin and Ukrainian President Volodymyr Zelenskyy involved in the talks, Beckman said.

The U.S. side of the negotiating effort was unusually small. Asked how involved the traditional White House national security apparatus was, Beckman said Trump handled the effort. "It's just the first lady," Beckman said.

"The devil is in the details," Beckman said of the negotiations. "There were moments in time where things became complicated." What began as an effort to get food, water and medicine to a city on the brink of collapse quickly became an extraordinarily detailed negotiation over how to temporarily stop two armies from fighting.

The agreement remains narrowly focused on humanitarian operations in and around Oleshky and does not halt fighting elsewhere in Ukraine, where Russian and Ukrainian forces continue to battle along a sprawling front.

Trump and Beckman worked through maps, roadways and aerial imagery with the two sides, Beckman said. They negotiated what military equipment could enter the area, how civilians would be evacuated and even arranged refrigerated trucks to recover bodies expected to be found along the way.

"We know all of the military equipment that will be brought in," Beckman said. "We even went as far as organizing for refrigerated trucks for the bodies that are going to be there."

"It's going to be a very bad scene," he added. "That's the level of detail that the first lady was involved in." The negotiations eventually produced a plan mapped out not just by weeks and days, Beckman said, but by the hour.

Russian and Ukrainian officials reconvened in Belarus at 4 a.m. New York time Friday for what was supposed to be a 5 a.m.g. But negotiations continued for nearly three more hours, with Trump participating by video, before both sides finally agreed to the terms and signed at 7:40 a.m.

The ceasefire was initially slated to begin Oct. 29, but the two sides moved the start up by two days, with the guns falling silent at 4 a.m. Moscow time Tuesday. Its geographic scope was also expanded beyond Oleshky to provide safe passage through the surrounding Kherson region for humanitarian convoys. "It was almost like momentum clicked," Beckman said.

Russian Gen. Valery Gerasimov, chief of the General Staff, confirmed Russian forces would cease fire along the Kherson axis and facilitate the safe movement of humanitarian convoys into Oleshky.

The humanitarian mission itself will be led by civilians from both countries, keeping Russian and Ukrainian troops apart as aid enters the city and residents are evacuated.

"If the Ukrainian, the Russian militaries were going throughout Oleshky, they would just kill each other," Beckman said.

Four American journalists from Newsmax will also accompany the mission to interview residents and document where they choose to go, providing a record of their decisions as civilians are evacuated from Russian-held territory.

The humanitarian mission is expected to last about one week, with a goal of wrapping in early November. If more time is needed, Beckman said both sides could negotiate an extension with the first lady again participating in the talks. The agreement also envisions a role for Trump beyond the immediate Oleshky operation.

Under the terms signed by the two sides, Russia and Ukraine are expected to establish regular humanitarian aid deliveries and repatriation efforts in communities across the Kherson region following the Oleshky mission, with Trump's assistance and coordination. Those efforts would take place as needed, but at least once a month, according to the agreement.