Russia, Europe and the United States must unite their technological potential to develop a missile defence system making it impossible for terrorists to attack them, Russian Prime Minister Mikhail Kasyanov told a news conference in Rome on Tuesday. Such a system will be much cheaper than the $60 billion that the United States intends to invest in its national missile defence system, Kasyanov said. The Russian initiative in this field makes impossible the use of the system against countries not possessing such systems, not only against terrorists, he said. Terrorists could deliver nuclear weapons using tools that the national missile defense cannot counter, Interfax cites Kasyanov as saying. "Other approaches to this problem are needed," he said.