NATO's top official on Monday defended the alliance's plan for a shield against ballistic missiles in Europe, insisting the system is on track despite two U.S. reports that describe it as over budget and plagued by technical problems. Secretary-General Anders Fogh Rasmussen said in an interview with The Associated Press the military alliance plans to announce its initial operational capacity at its summit in Chicago next month and that tests of the missile defense system show it is working. "This will make it possible to protect parts of NATO territory, and that concept will be further developed in the coming years so that we will gradually be able to protect all the populations in European NATO countries," Fogh Rasmussen said. As far as NATO is concerned, we have tested the systems and they work. Reports by the Defense Science Board, an advisory group to the U.S. Defense Department, and the U.S. Congress' Government Accountability Office, indicated the system is plagued by technological problems, delays and cost overruns. The reports say missile interceptors are running into production glitches, radars are underpowered and sensors cannot distinguish between warheasds and other objects. Fogh Rasmussen declined to discuss specifics, saying he had not seen the reports. "I think that's a U.S. question," he said. Missile defense in Europe has been a nettlesome issue since the middle of last decade, when President George W. Bush announced plans to base long-range interceptors in central Europe as a defense against missiles from Iran. That infuriated Russia, which believed the program was intended to counter Moscow's intercontinental ballistic missiles and undermine its nuclear deterrent. NATO Secretary General Anders Fogh Rasmussen speaks with the Associated Press at NATO headquarters in Brussels on Monday, April 30, 2012. NATO's top official is vigorously defending the alliance's plan for a shield against ballistic missiles, despite two U.S. reports which cast doubt on project's technical and financial feasibility. (AP Photo/Virginia Mayo) Close Soon after Obama took office in 2009, he revamped the program with a plan calling for slower interceptors that would be upgraded gradually over four phases, culminating with the newest versions in 2020. NATO says that the future ballistic missile defense system passed a significant technical test on 4-5 April during a series of simulated engagements. In another April test, a similar theater missile defense system tested jointly with Russia also performed well, it says. Critics have dismissed the missile shield as an expensive "make-work project" designed to provide the 63-year-old alliance with a raison d'etre after it winds down its presence in Afghanistan. Fogh Rasmussen said leaders will discuss ending the alliance's combat operations in Afghanistan by the end of 2014, while remaining committed to the training mission after that. He said he was confident that the international community - not just the U.S., NATO and other partner nations engaged in the war - will commit itself to help finance Afghan security forces after 2014. "The reason is that from a political point it's much better to give the defense of Afghanistan a strong Afghan face by handing over the full responsibility to the Afghan security forces, and from the economic point of view it's less expensive to finance Afghan security forces than to deploy foreign troops," he said. Fogh Rasmussen also said he felt confident that whoever wins Sunday's French presidential election, the country will stay committed to the operation in Afghanistan based on the principle "in-together, out-together." Polls predict that incumbent Nicolas Sarkozy will lose the May 6 runoff to Socialist Francois Hollande, who has vowed to speed up the timetable for a pullout of France's 3,600 troops from Afghanistan by the end of this year. "NATO as an organization deals with the elected president whoever it may be," Fogh Rasmussen said. We know France as a staunch and reliable ally (in Afghanistan). Raf Casert in Brussels contributed to this report.