“History including the US is about territorial expansion, borders change, some changes are precipitated by force. See Mexican American War..”
This does not compare with the Mexican - American war. The Ukrainian Army has not assaulted a Russian outpost or base. The Mexican-American war was started by a Mexican Army attack on a US outpost. They lost and agreed to giving up territory to settle it. Otherwise Mexico would be a bunch of US states as the US Army occupied most of north and central Mexico at the time. That is the “territorial expansion” that occurred in the Mexican - American war.
And Happy Texas Independence day.
What about the Iraqi occupation of Kuwait in 1990 due to theft of Iraqi oil through directional drilling? The difference? Realpolitik: Russia has the Bomb and Iraq didn’t.