What is the relationship between Guam and the United States?

Guam is indeed a U.S. territory, and all residents of Guam are U.S. citizens. Those born in Guam naturally possess U.S. citizenship.

To put it simply, if the 50 states in the continental United States are "blood sons", then Guam is equivalent to the "godson". Why treat them differently? In the final analysis, it is because Guam is actually a colony snatched from Spain by the United States.

Since 1565, the Spanish have occupied Guam as their colony. When the United States won the Spanish-American War in 1898, it seized Guam from Spain and built a military base. During World War II, the Japanese army occupied Guam in 1941, and the US military recaptured it again in 1944. After the end of World War II, the US military rebuilt its military base in Guam.