What can United States do in 18 months? US has been being there since 2001 and there is no progress in Afghanistan. This is the longest war for United States. Obama just want sure the public amid the US public do not support US Government for the Afghanistan war.
Obama cannot guarantee Taliban will be defeat in 18 months with 30,000 additional troops and the Karzai government will be free from corruption.
If Obama cannot guarantee, he should stop this war before late.