We weren’t at war with them. We had won the wars and new governments were elected, who asked us to stay there to provide security. Why wouldn’t a government that wanted to be our ally, was dependent on us for its security, want to help us with our disaster? Even countries that were not our allies and were outright antagonistic with us offered aid (Cuba, Iran, Venezuela). In that case it is at least partly a diplomatic ploy to make us appear to be the bad guy for refusing their aid while our people are suffering. Meanwhile they look like the good guy willing to help the suffering people of their enemy.