please check if the structure of sentences are correct

1)After Barack Obama achieved power, the US policy towards their military presence changed. The US president announced the reduction and withdrawal of its troops that caused several major problems in Afghanistan, such as the enhancement of terrorist groups, especially the Taliban and ISIS, and that political and economic insecurity and instability that led to brain drain, emigration, and capital flight from Afghanistan.

Finally, I will end my speech with a conclusion. I want to say that whatever happens to Afghanistan after the withdrawal of American and allied forces, all countries will suffer while being responsible.