I really don't want to open this can of worms too far. Though it is impossible for me not to continually feel the need to point out how many countries USA and Nato have invaded in the last 80 years.
Any country where attacks against our homeland were launched from would be justifiably under self-defense.
GW2? Meh. Iffy. Really just finishing up GW1 and Sadaam still refused to comply with the conditions of the last ceasefire. We had a standing UN authorization to use force in Iraq. We exercised our mandate. Did Russia have UN authorization to invade Ukraine? Had military operations against Russia been launched from Ukraine to justify a self-defense argument?
None of our military interventions have been for the purpose of naked territorial acquisition. Putin isn't defending against an attack. He wants that territory and simply wants to take it by force.
You'd have to go back to the Philippine Insurrection to find that for the US, and yes I think were were wrong back in 1899.
And sorry, which countries has NATO invaded for the purposes of land acquisition?