(CNN) -- The United States will phase out its stockpiles of landmines designed to target people, moving closer to joining a global ban on a weapon that kills more than 15,000 people a year -- most of them civilians.
U.S. officials made the declaration at an anti-mine conference in Maputo, Mozambique, according to a statement issued by National Security Council spokeswoman Caitlin Hayden.
Activists have long pressured the United States to join the international treaty banning the production, stockpiling and use of anti-personnel landmines -- the kind meant to kill or maim when someone steps on them.
Such mines are easily triggered when stepped on, unlike anti-vehicle mines. Those weapons can still kill, but only go off when heavy vehicles pass over them.
Anti-personnel mines, many of them placed during earlier conflicts dating back years, kill more than 15,000 people a year, according to the United Nations. Thousands more are maimed.
As of last year, 161 nations were parties to the treaty, commonly known as the Ottawa Convention, but major powers including the United States, China and Russia are not, according to the Arms Control Association.
In a statement, Hayden said, "Our delegation in Maputo made clear that we are diligently pursuing solutions that would be compliant with and ultimately allow the United States to accede to the Ottawa Convention."
She said other aspects of U.S. landmine policy remain under review.
The White House later issued a statement saying "the United States shares the humanitarian goals of the Ottawa Convention."
Activists welcomed the U.S. statement.
"The message to the international community is clear -- the Mine Ban Treaty is the only solution to eliminate the suffering caused by landmines," said the head of the International Campaign to Ban Landmines delegation to the Maputo conference.
But some criticized the United States for failing to commit to a ban on the use of its current stockpiles of mines, and chastised the Obama administration for failing to set a date to join the treaty.
"By not setting a firm date to complete this task, the U.S. runs the risk of allowing its landmine policy review to drift beyond President Obama's term in office as president," said Elizabeth MacNairn, executive director of Handicap International U.S.
More than 100 million mines are believed to be in stockpiles around the world, with millions already in the ground in 59 countries, according to the Arms Control Association.
In 1997, the Clinton administration made a goal of joining the treaty by 2006, but President George W. Bush reversed the decision in 2004, according to Human Rights Watch.
In a policy announced that year, the United States said it would no longer use mines made to be invisible to metal detectors and those that don't self-destruct after a set time.
In 2009, the United States announced a comprehensive landmine policy review. Anti-landmine activists had been pressuring the Obama administration to announce the results of that review before the Maputo conference.
Despite not being part of the treaty, the United States is the largest donor worldwide to efforts to combat landmines and help victims, providing more than $2 billion in aid since 1993, according to the International Campaign to Ban Landmines.