A car bomb believed planted by a left-wing terrorist group exploded Tuesday and killed the U.S. military attache in Greece, hurling his armor-plated car off the road, authorities said. U.S. Navy Capt. William Nordeen was driving to work when the blast threw his sedan across the small tree-lined street and lodged it in a steel fence, police said. The victim's body was found several yards away in the front yard of an abandoned house. There was no immediate claim of responsibility for the blast, but senior police officials said they believed it to be the work of November 17, a left-wing urban terrorist group blamed for 11 political assassinations in the past 13 years. The United States and Greece both condemned the bombing, which came a a crucial time in relations between the two countries. ``The United States condemns this terrorist outrage in the strongest possible terms,'' said chief Pentagon spokesman Dan Howard. ``It was a senseless and cowardly murder of a highly regarded U.S. military officer.'' Sotiris Kostopoulos, a spokesman for Foreign Minister Carolos Papoulias, said the Greek government voiced ``disgust at the murder.'' ``All Greeks, irrespective of their political leanings, unreservedly condemn the would-be underminers of the country's institutions and democratic normality,'' Kostopoulos told reporters at a news briefing. Police said the Toyota packed with explosives was parked 100 yards from Nordeen's two-story home in the northern suburb of Kifissia, where many American and foreign diplomats live. The blast shattered windows and blew out doors in surrounding houses. Trees, fences and walls were blacked by smoke after fire engulfed both cars. ``We heard a tremendous bang and the house rocked back and forth. Pieces of the car were thrown into our house,'' Panagia Kapodistria said. The car's twisted rear axle lay in her front yard. Nordeen, 51, of Centuria, Wis., was due to retire in August after 30 years in the Navy, said his sister, Carla Anderson. He had been stationed in Greece for three years. He previously served as assistant naval inspector in Washington, with the U.S. Fleet in the Pacific and at the Jacksonville, Fla., naval air base. He is survived by his wife and 12-year-old daughter. At the White House, presidential spokesman Marlin Fitzwater said the U.S. government would work with Greek authorities to ``bring the murderers to justice.'' A senior police officer, speaking on condition of anonymity, said he believed it was staged by November 17, named for the day in 1973 when troops crushed a student rebellion at Athens Polytechnic University against the right-wing dictatorship. ``I don't think anybody except November 17 had the expertise to pull off something like this,'' the officer said. A police explosives expert who refused to be identified said Tuesday's killing was ``perfectly planned and very well executed. ... They thought of every detail.'' The expert said bags of cement were piled against one side of the booby-trapped vehicle so the explosion's full force would be directed toward Nordeen's car. He said the blast probably was detonated by remote-controlled device. November 17 carried out a similar attack against the U.S. Drug Enforcement Agency's local chief in January, but George Carros survived after the radio-controlled bomb in a trash can outside his home failed to go off. The group has claimed responsibility for 11 assassinations since 1975, including the 1983 shooting of U.S. Navy Capt. George Tsantes and the 1975 assassination of Richard Welch, CIA station chief in Athens. November 17 is named for the day in 1973 when troops crushed a student uprising against the 1967-74 Greek military dictatorship. Nordeen's killing came four days after Greek and American negotiators ended a seventh round of talks on a new U.S. bases agreement to replace an accord that expires Dec. 31, 1988. The talks ended without reports of significant progress. The United States has operated four military bases in Greece since the 1950s _ two near Athens and two on the island of Crete. The five-year accord expires in December 1988.