U.S. acceptance of a treaty banning landmines is “long, long overdue” and U.S. President Barack Obama should use a 10-year review this weekend to announce plans to join the accord, anti-landmines campaigners said on Monday. The treaty, which went into action on March 1, 1999, bans the use, stockpiling, production or transfer of antipersonnel mines. It has been endorsed by 156 countries, but several powers—including the United States, Russia, China and India—have not yet adopted it. The United States is sending a State Department observer delegation to the treaty's second five-year review conference on Sunday in Cartagena, Colombia, the first time it has attended a gathering of states that have accepted the treaty. “The very fact that they are showing up we take as a positive sign of movement on this issue within the Obama administration,” said Steve Goose, director of the Arms Division of Human Rights Watch. “We hope they're not coming empty-handed,” he said, adding “we very much want them to come and say that they intend to join this convention. Even if they can"t give a timeline, we want them to say they intend to join at some point in time.” Goose said a declaration of intent was particularly important because the administration of former U.S. President George W. Bush reversed U.S. policy on accepting the convention and said it would never join. “We're the only country in the world that has said out loud we do not ever intend to join this convention,” he said. Campaigners said the treaty has been enormously successful since it went into force, cutting land mine casualties by about half, sharply reducing the use of the weapons and encouraging relief efforts for victims. The international effort that led to the treaty won the 1997 Nobel Peace Prize.