"The United States has increased its military spending by 81 percent since 2001," Stockholm International Peace Research Institute (SIPRI) reported.
Other reports say the US -- with its costly military operations in Afghanistan and Iraq -- has increased spending by nearly 3 percent.
"At 4.8 percent of gross domestic product, US military spending in 2010 represents the largest economic burden outside the Middle East," said SIPRI Military Expenditure Project chief Sam Perlo-Freeman.
Last year, the Unites States increased spending by 2.8 percent to USD 698 billion - about six times as much as China, the second-biggest spender ahead of Britain, France and Russia. In 2009, US spending grew 7.7 percent compared to a year earlier.
The US has reportedly spent over USD 1 trillion in taxpayer money on its wars in Iraq and Afghanistan since 2001.
Polls show that American voters support cuts in military spending
