The US administration is planning to cut its war budget by $42bn with a reduction of troops levels in Iraq and Afghanistan.
The proposed $117bn budget for fiscal year 2012 is a 26% decrease from the 2011 level and would be the lowest expenditure for wars since 2005.
The war-spending request is expected to be presented to Congress in the week starting 14 February, along with a $553bn defence base budget for fiscal 2012.
Center for Strategic and Budgetary Assessments analyst Todd Harrison said the proposal is the largest year-to-year decrease in total war funding since the Afghan war began.
"With a year-to-year reduction in war funding of this magnitude, it appears to signal an intent to continue the withdrawal from Iraq and to begin reducing troop levels in Afghanistan during fiscal 2012," he added.
About 144,000 US troops are currently deployed, with 97,000 troops in Afghanistan and 47,000 in Iraq. Those in Iraq are scheduled to leave the country by the end of this year.
The Pentagon has spent a monthly average of $4.3bn in Afghanistan and $3.4bn in Iraq for the first three months of the 2011 fiscal year, according to Bloomberg.