Ukraine captured two wounded North Korean soldiers who were fighting on behalf of Russia in a Russian border region, South Korea’s intelligence service said.

The partnership, according to officials who spoke to ABC News, has been essential to Ukraine defending itself as Russia invaded almost three years ago.

About 1,000 North Korean soldiers are believed to have been killed while fighting Ukrainian forces in Russia's western front-line region of Kursk, a news report said Thursday. Out of the estimated 11,

In a statement posted on X, Zelenskyy said he had instructed Ukraine's security service to allow journalists access to the captured soldiers.

South Korea's intelligence agency estimates that approximately 300 North Korean soldiers have been killed and another 2,700 injured while fighting alongside Russian forces against Ukraine. This marks North Korea's first participation in a large-scale conflict since the 1950-53 Korean War.

The soldiers of the Korean People's Army captured from the front lines of the war in Ukraine appeared unwilling to defect from North Korea.

Ukraine has captured two injured North Korean soldiers from the battlefield in Russia’s Kursk region and transferred them to Kyiv, Ukrainian President Volodymyr Zelenskyy said on Saturday.

Ukrainian forces fighting in Russia's Kursk Oblast captured two North Korean soldiers, President Volodymyr Zelensky announced on Jan. 11, "irrefutable evidence" of Pyongyang's involvement in Moscow's full-scale invasion.

Separately, Ukraine revealed more details about the first two North Korean soldiers it has captured alive and said it was willing to exchange them for Ukrainians held in Russia.

Ukrainian President Volodymyr Zelenskyy predicted that his nation's forces would "undoubtedly" capture more North Korean troops.

Ukraine released no audio recording of the prisoners but said they were talking through Korean interpreters working "in cooperation" with South Korea's National Intelligence Service (NIS).

Russia has lost about twice as many men to death and serious injury as Ukraine. But the trends favor the Kremlin.