Famously, Germany and Japan. That brought stability to Western Europe for, broadly speaking, the whole of the 20th century.
Backstopped by Nato (which is, in essence, a threat that the US will bomb you) which has, largely successfully, deterred the USSR and Russia.
More recently, Kosovo and Bosnia, ending ethnic cleansing and leaving statues, streets and babies across the region named for Clinton and Blair. Granada and Panama are more controversial but are stable.
In Korea the US only really managed to maintain its power in the south of the peninsula. You are welcome to your own view on whether the north or south is more stable and which brand of stability you would prefer.
Plenty of failures of intervention too. But anyone unaware of WWII should first wonder if they are fully equipped yet to judge this complex question.