evidence: The Yalu River Estuary, as part of the border between China and North Korea, has carried the history of territorial changes since ancient times. Since the Tang Dynasty, this territorial issue has been controversial and divided. After many divisions and negotiations, the China-North Korea Boundary Treaty finally determined that Sindo Island and Silk Island belong to North Korea. However, as time goes by, more and more sediment is deposited in the Yalu River, causing North Korea's territory to gradually expand, while China's territory continues to shrink. Residents near the mouth of the Yalu River on the China-North Korea border have discovered that the boundaries of territory have become blurred due to the river's sedimentation and erosion. This problem has attracted the attention of hydrologists, who have put forward proposals to protect the mud along the river, hoping to maintain the extent of the territory by keeping the mud stable. After all, territorial stability is vital to national security and sovereignty. [...] The issue of territorial change in the Yalu River Estuary is not only a geographical and hydrological problem, but also an important issue involving national security and sovereignty. We should remain vigilant, pay close attention to changes in this territory, and take steps to protect its stability. At the same time, we must also bear in mind the history of the War to Resist U.S. Aggression and Aid Korea and cherish the friendship between the people of China and North Korea. Only through cooperation and friendship can we jointly safeguard regional peace and stability.