Near-Earth Objects (NEOs), particularly Potentially Hazardous Asteroids (PHAs), pose a persistent risk to Earth. Improving early detection, precise tracking, and physical characterization of these objects is essential for reliable impact-risk assessment and the development of effective planetary-defense strategies. This talk will provide an overview of recent progress in ground-based optical monitoring, including survey optimization, astrometric and photometric data processing, and follow-up observations supported by international networks. I will highlight Korea’s expanding contributions within the International Asteroid Warning Network (IAWN), and introduce the SEJONG telescope, a newly developed 1.5-m facility dedicated to NEO discovery. Our efforts focus on advancing automated moving-object detection pipelines and establishing optimized observing strategies to increase the detection efficiency. I will also present our development of an impact-probability estimation tool to more accurately assess the threat posed by newly detected objects. Finally, I will introduce our concept for a future planetary-defense mission, provisionally named FINALEI, which aims to conduct a flyby to characterize a target asteroid’s physical properties and subsequently perform a kinetic-impact experiment on a secondary asteroid to alter its orbit. The ultimate objective of this mission is to enable an active planetary-defense capability.