Easy - cut all funding not tied to their withdrawl. This isn't the fall of Siagon. If it is planned properly, it can be done with no more loss of life than we would see if we stayed for the same length of time that it would take to withdraw.
No matter the details of the plan, there is no question but that we will lose more lives if we postpone it, because the withdrawl will pose the same risks, but we will lose more lives in the time leading up to the withdrawl.
If you are convinced that it is a lost cause, you have to demand an immediate withdrawl. There is no room for middle ground here. Either it is a lost cause, or not. If it is, get the troops out. If it is not, stop undermining the troops and their morale...