The White House said Tuesday that it regrets Russia's decision not to attend preparatory meetings last week for the 2016 nuclear security summit. White House spokesman Josh Earnest told reporters that Russia decided not to participate in the meetings but that he was not aware that Moscow planned to boycott the actual summit itself. "The United States regrets Russia's decision not to participate in last week's preparatory meeting for the 2016 Nuclear Security Summit," Earnest said. "As far as the United States, the door remains open to Russian joining future meetings like this." The fourth nuclear security summit will be held in Chicago, Illinois, in 2016, returning to the United States, where President Barack Obama launched the process in 2010. "We'd hope that Russia still shares the view that securing loose nuclear materials in combating the threat of nuclear terrorism remains a priority well worth the personal attention of world leaders," Earnest said. The summits intend to enhance nuclear security around the world and have involved major powers including China, France, Germany, and Britain.