The cost of the wars unleashed by President George W Bush's government could exceed $1 trillion by the end of his term of office, predicts a study by Centre of Defence Information (CDI).
The report said the expenses on the White House military adventures would range between $980 billion and $1.4 trillion by early 2009.
The attacks on Iraq and Afghanistan have cost over $500 billion to the US contributors.
According to the study the Congress has devoted $510 billion to the military actions overseas, from late 2001 to September 2006, excluding the Pentagon's huge annual budgets.
The report specified that the expenses on the invasion and occupation of Iraq reached $378 billion and the operations in Afghanistan took $99 billion.
The allocations to other actions in US territory and overseas, considered as the so-called war against terrorism, reached $28 billion.
The Centre for Defence Information is a non-governmental research institute and provides expert analysis on various components of US national security, international security and defence policy.