Complex sentence: On July 17, the NK 5th Division entered Yongdok, taking the city without much resistance before fierce UN counterattacks caused the division heavy losses to air attacks still, it was able to surround the ROK 3rd Division in the city.
Split into simpler sentences: On July 17, the NK 5th Division entered Yongdok, taking the city without much resistance before fierce UN counterattacks caused the division heavy losses to air attacks. Still, it was able to surround the ROK 3rd Division in the city.