Three protesters, arrested amid tight security ahead of the NATO summit in Chicago, have been charged with terrorism for possession of explosive devices.
The three were arrested Wednesday, and police said they were being held for a hearing Saturday. Six others arrested at the same time were released Friday.
Supporters of the three say the suspicious equipment was just part of a beer-making kit.
Officials from more than 50 countries are convening for the two-day NATO summit that starts Sunday to discuss a variety of issues affecting the alliance's future.
Afghanistan is expected to dominate the agenda of the gathering, hosted by U.S. President Barack Obama.
The alliance is planning to gradually hand over security control to Afghan forces and pave the way for the withdrawal of some 130,000 foreign combat troops by the end of 2014.
NATO chief Anders Fogh Rasmussen has said that Pakistan has an important role in the plans and invited Pakistani President Asif Ali Zardari to the summit. Pakistan this past week agreed to reopen a key NATO supply route through its territory into Afghanistan.
Islamabad closed the route about six months ago when U.S.-led air strikes killed 24 Pakistani soldiers on the border with Afghanistan.
Newly-elected French President Francois Hollande is also attending the summit. He told President Obama during a meeting Friday that he will fulfill his campaign promise to withdraw 3,500 French troops serving in Afghanistan by the end of the year, almost two years ahead of schedule. But he said his country will continue to support the Afghan mission, in a different way.