Anti-landmine campaigners meeting in Nairobi have accused the United States of setting a dangerous example by refusing to sign up to a worldwide ban.
Campaigners are urging the US to sign up to the landmine ban
The US says it has valid reasons to use anti-personnel landmines, particularly to protect its troops in South Korea.
More than 140 countries are signatories to the 1999 Ottawa Mine Ban Treaty.
But delegates say action from the US is vital to pushing on with efforts that have so far seen 40m devices detonated and stockpiles destroyed.
The Ottawa convention bans the production, stockpiling and use of anti-personnel landmines.
Dozens of countries have destroyed their stockpiles of mines and countless lives and limbs have been saved, says the BBC's Stuart Hughes from the summit.
But the US, which has stocks of 10m landmines, is the most notable absentee from the treaty and from the list of countries represented at the Nairobi conference.
It is the world's biggest donor to mine clearance programmes and is not thought to have planted any new mines since the 1991 Gulf war.
But the Bush administration announced earlier this year that it would not sign up to the treaty.
Steve Goose, of Human Rights Watch, said: "There are states who like to maintain that they won't join the convention until the US joins.
"So it's hurting our efforts to further universalise, to bring the rest of the world on board."
Activists are also concerned about America's research into so-called "smart mines" which self destruct within a few hours or weeks.
They say such mines can fail - although there is dispute about the figures - and can be just as difficult to clear as traditional or "dumb" landmines.
Delegates are putting forward a five-year action plan to try to end the suffering caused by landmines, but they fear it will be toothless without US engagement.