Ruud Lubbers, a former Dutch prime minister, is all but certain to become the next NATO chief after a key endorsement today by German Chancellor Helmut Kohl. The secretary-general's post has been open since Willie Claes resigned earlier this month over an unrelated Belgian corruption scandal. "The Kohl endorsement is critical, because Germans resented Lubbers' opposition to the reunification of Germany," reports Brussels bureau chief Jay Branegan. "Since Kohl blocked Lubbers from becoming president of the European Commission, he probably feels the score has been settled. Lubbers is highly regarded by the rest of the NATO countries, especially the U.S., which see him as a skilled power broker who can handle the sensitive alliance." Britain and France already in support the 56-year-old Lubbers to lead the 16-nation military alliance.