First please note my corrections to your post, marked in red. It is important to follow these rules of written English:
- Start every sentence with a capital letter.
- End every sentence with a single, appropriate punctuation mark.
- Always capitalise the word "I".
- Capitalise all proper nouns (English, Italy, Microsoft, Shakespeare etc.)
- Do not put a space before a full stop, comma, question mark or exclamation mark.
- Always put a space after a full stop, comma, question mark or exclamation mark.
The main gist of the piece is that Barack Obama is listening to the advice of his military advisers, although the writer thinks that he has started listening to this advice later than he should (he should have started listening to them earlier). "Amid deteriorating security" means "at the same time that security is deteriorating in Afghanistan.
"This" refers to Obama's belatedly heeding the advice.
Reading articles is a good way to practise your comprehension. It should also help you to learn how English sentences are constructed - grammar, capitalisation, spacing and punctuation (as long as you read well-written articles).
Student or Learner