The U.S. has 8,892 forces in Iraq, 15,298 troops in Afghanistan and 1,720 in Syria, for a total of 25,910 troops serving in the three war zones as of Sept. 30, according to DOD.
A March 2011 Congressional Research Service report noted, following the Afghanistan surge announcement in 2009, Defense Department spending on Afghanistan increased by 50%, going from $4.4 billion to $6.7 billion a month. During that time, troop strength increased from 44,000 to 84,000, and was expected to be at 102,000 for fiscal year 2011. The total cost from inception to the fiscal year 2011 was expected to be $468 billion. The estimate for the cost of deploying one U.S. soldier in Afghanistan is over U.S.$1 million a year.
During the nearly 17 years since the United States went to war in Afghanistan, the number of American troops went up to 100,000 (in 2011), then dropped slightly below 10,000. President Barack Obama had planned to drop the number to 5,500 by the end of 2016. They were at declared level of 8,400 through the end of his presidency.