An anti-landmine summit in Kenya has called on the world's major powers to sign up to a global ban on the devices.
Mr Annan said the treaty as a "remarkable success story" of cooperation
United Nations Secretary General Kofi Annan urged the big players to join "a remarkable success story in the history of international co-operation".
The US, China and Russia are among 40 nations which are not party to the 1999 Ottawa Treaty banning landmines, signed by 144 countries.
Washington on Friday rejected the call, citing its military responsibilities.
Instead, the State Department defended America's record as a leading supporter of global demining initiatives, that was also trying to promote so-called "smart mines" which deactivate themselves after a period of time.
"The United States has taken the lead in this regard, although we do still have some military responsibilities around the world that prevent us from, at this moment, signing the Ottawa treaty," State Department spokesman Richard Boucher said.
Delegates at the Nairobi summit adopted a five-year plan mapping out the clearing of minefields, ending stockpiles, and victim welfare.
The summit's final declaration stated: "We call upon those states that have not joined our efforts, particularly those that possess vast stocks of anti-personnel mines or continue to use this insidious weapon, to adhere to the convention without delay."
The treaty bans the production, stockpiling and use of anti-personnel landmines.
But delegates said earlier a commitment from the US was vital to push on with efforts that have so far seen 40 million mines detonated and stockpiles destroyed.
Mr Annan, addressing the conference in a video link from New York, said: "The anti-personnel mine ban treaty is a remarkable success story in the history of international co-operation, but there is much more still to be done.
"We must persuade more states, including some of the world's largest, to become parties to the treaty.
"And we must do more to help the victims of land mines to rebuild their lives and support themselves."
China indicated at the convention that it was ready to speed up the removal of mines.
Liu Jieyi, China's head of arms control and disarmament told members: "We stand ready to further expand our co-operation with the states (that are) party to the convention, in order to contribute to early elimination of landmines."
The action plan contains a timetable for continuing the removal of landmines, the destruction of stockpiles and providing aid to mine victims.
There are an estimated 400,000 landmine survivors in 121 countries, most of them developing nations.
Jody Williams, 1997 Nobel Peace Prize winner and founder of the International Campaign to Ban Landmines, said: "The success of the Nairobi summit will be measured by how vigorously the action plan adopted this week is carried out."