More than 90 countries have approved a treaty designed to clean up unexploded weapons following conflict.
The treaty signed at the United Nations in Geneva gained support of major powers, including the United States.
It is the first time the Bush administration has signed an international arms agreement.
Thousands of civilians are killed by unexploded arms - known as "sleeping weapons" - years after wars have ended, say aid agencies.
Under the treaty, governments have promised to "mark and clear, remove or destroy explosive remnants of war in affected territories under its control".
It includes the controversial cluster bomb which has been used by the US in Afghanistan and Iraq.