It's not international territory in any way, it's US territory. International airports being ports of entry is a bit of a legal fiction, because it's not feasib

It's not international territory in any way, it's US territory. International airports being ports of entry is a bit of a legal fiction, because it's not feasible to conduct immigration and customs inspection immediately when the airplane enters US airspace. That doesn't mean that it's not US territory in any way. Aliens (with certain exceptions) need either a US visa or an ESTA to transit through the United States. Technically speaking, the Immigration and Nationality Act permits transiting through the United States without a visa if certain conditions are met, but in practice this is not allowed anymore.