Nearly nine months after losing chunks of the Kursk region to a surprise Ukrainian incursion, Russia announced that its troops have fully reclaimed the border territory.

Ukraine denied it, saying the fighting was still ongoing. If confirmed, Moscow’s victory in Kursk would deprive Kyiv of key leverage in U.S.-brokered efforts to negotiate an end to the more than 3-year-old war by exchanging its gains for some of Russia-occupied land in Ukraine.

Here are key moments of the battle for Kursk and its impact:

A Ukrainian blitz

Ukrainian forces pushed into Kursk on Aug. 6, 2024, in a surprise attack, with battle-hardened mechanized units quickly overwhelming lightly armed Russian border guards and inexperienced army conscripts. Hundreds were taken prisoner.

The incursion was a humiliating blow to the Kremlin — the first time the country’s territory was occupied by an invader since World War II.

It was plotted in complete secrecy, with the Ukrainian troops involved reportedly told their mission only a day before it began. Russia’s drones and intelligence assets were focused on battlefields in eastern Ukraine, which enabled Kyiv to pull its troops covertly to the border under the cover of thick forests.

Ukrainian units quickly drove deep into the Kursk region in several directions, meeting little resistance and sowing chaos and panic. As the most capable Russian units were fighting in the Donetsk region of eastern Ukraine, Moscow didn’t have enough land forces to protect the Kursk region and other border areas.

Ukrainian President Volodymyr Zelenskyy cast the incursion as a way to distract Russian forces in the east and said Kyiv could eventually exchange its gains for Russian-occupied territory in peace talks.

Ukraine’s chief military commander, Gen. Oleksandr Syrskyi, said Kyiv’s forces captured nearly 1,300 square kilometers (500 square miles) and about 100 settlements in the region that covers 29,900 square kilometers (11,540 square miles). Unlike the static front lines in Donetsk, Ukrainian units were able to roam the region without establishing a lasting presence in many settlements they seized.

While the incursion came as a much-sought morale booster for Ukraine amid battlefield setbacks, skeptics saw it as a dangerous gamble that distracted some of its most capable forces from Donetsk, where Kyiv was steadily losing ground to the Russian offensive.

Russia’s slow response

In the incursion’s opening days, Russia relied on warplanes and helicopters because it lacked ground forces to stop the onslaught.

At the same time, Moscow began pulling a motley collection of reinforcements from all over Russia, some of whom lacked combat experience and had trouble coordinating with each other, contributing to Ukraine’s swift gains.

But contrary to Kyiv’s hopes, the incursion didn’t force Moscow to shift a significant number of troops there. Since Russia lacked the resources to expel the attackers quickly, it focused on stemming deeper Ukrainian advances by sealing roads and targeting Kyiv’s reserves.

North Korea’s role

In the fall, Ukraine, the U.S. and South Korea said North Korea, which previously had supplied weapons to Moscow, had deployed 10,000-12,000 troops to Russia to fight in Kursk.

Moscow and Pyongyang initially responded vaguely to the reports of the North Korean deployment, emphasizing that their military cooperation conforms with international law, without directly admitting the troops’ presence.

On Saturday, Russia’s General Staff chief Gen. Valery Gerasimov confirmed that North Korean soldiers in Kursk took part in “combat missions shoulder to shoulder with Russian servicemen during the repelling of the Ukrainian incursion.” He praised them for having “demonstrated high professionalism, showed fortitude, courage and heroism in battle.”

While North Korean soldiers are highly disciplined and well trained, Ukraine and its allies said they suffered heavy casualties from drone and artillery attacks due to their lack of combat experience and unfamiliar terrain.

In January, South Korea’s National Intelligence Service said about 300 North Korean soldiers had died and another 2,700 had been injured. Zelenskyy had earlier put the number of killed and wounded North Koreans at 4,000, although U.S. estimates were lower, about 1,200.

South Korea’s spy agency said in February that North Korea apparently had sent additional troops to Russia.

Russia intensifies efforts to reclaim Kursk

The Kremlin bolstered Russian forces in Kursk in the fall, and they gradually intensified their effort to drive out the Ukrainians.

By February, Russia reclaimed about two-thirds of the captured territory, leaving Ukraine with an area around Sudzha, a border town that was Ukraine’s main hub in the region.

Pressure on Ukrainian troops sharply increased in March, when Russian forces sought to cut a corridor between Sudzha and Ukraine’s Sumy region across the border. Russian artillery and drones relentlessly pummeled the road, which was littered with the carcasses of military hardware that made it hard for Ukraine to ferry supplies and rotate troops.

The interdiction of supply routes put Ukrainian forces in a difficult position, said Michael Kofman of the Carnegie Endowment. “As the Kursk pocket got squeezed, it became increasingly unsustainable,” he observed.

In a daring raid in early March, 600 Russian troops crawled 15 kilometers (over 9 miles) through a natural gas pipeline and emerged near Sudzha to strike Ukrainian troops from the rear.

The operation came as the U.S. halted weapon supplies and intelligence-sharing with Ukraine, a move that followed an acrimonious White House meeting on Feb. 28 between Zelenskyy and President Donald Trump. After talks with Ukraine on March 11, when Kyiv agreed to accept a 30-day ceasefire proposal, the U.S. said it was unfreezing the assistance.

Consequences for Ukraine

Ukraine’s military General Staff dismissed Moscow’s claim of reclaiming full control of Kursk.

If confirmed, Russia’s victory in Kursk would weaken Kyiv’s hand in peace talks, removing its bargaining chip for exchanging territory it lost earlier in the war.

Russia holds about a fifth of Ukraine, and Kyiv’s defeat in Kursk also raises the threat of Moscow’s farther advance in the Sumy border region.

On a visit to Russian military headquarters in Kursk last month, President Vladimir Putin set the task of carving a “security zone” along the border, a signal his military was considering a possible foray into Sumy.

Gerasimov said Saturday that the efforts to create a security zone in Sumy’s border areas were ongoing, and that the Russian military controlled over 90 square kilometers (35 square miles) there.

___

Follow AP’s coverage of the war in Ukraine at https://apnews.com/hub/russia-ukraine