About two dozen Greenpeace activists chained themselves together to block a side exit at a military airfield when U.S. President Bush arrived for a NATO meeting in Brussels today. They held up the sign, “George W. Bush — Wanted for crimes against the planet.” The side exit had been used by former President Clinton when he landed there, but Bush’s motorcade left the airport by the main exit, away from the protesters. Some 300 protesters collected outside NATO headquarters as country delegations arrived. Yesterday, Greenpeace activists in Norway boarded an oil tanker headed for the U.S., in the second such protest by the group this week. Greenpeace’s Steve Sawyer said, “We’re going after all the American oil we can get our hands on.”