"Who controls the past controls the future...."
I bet the US and UK governments are ruing the day they decided to interfere in Iran's democratic affairs back in 1953.
What with Reagan shooting his mouth off about the Russians, a deepening cold war (not helped by the Iran/Iraq war - US and allies backing Iraq, the Soviet Union backing Iran), the Soviets deploying to Afghanistan....all in all, not a great time to be growing up as a teenager aware of world affairs. I really thought the world was about to bite the big green nuclear banana between 1980 and 1985.
It's almost like nothing in international affairs is static, things change, and things being one way in one decade and another in a different decade doesn't mean anything or anyone is "wrong."
But basically the US decided helping the people who lost the war reconstruct can keep our influence in the area and reduce the desire to rise back up and retaliate against them.
The US actually tried exactly this same approach after the Afghanistan and Iraq wars (remember all the money spent on rebuilding afterwards, training police forces, etc?), and it turned out to not work out so well for them this time around.