UN Secretary-General Ban Ki-moon praised the United States for showing "flexibility" after delegates approved a "roadmap" for negotiating a new global warming pact, but warned the most difficult work lay ahead. "This is the beginning, not the end," he said in an interview with The Associated Press, minutes after officials from nearly 190 nations succeeded in breaking a deadlock at the UN climate meeting. "We will have to engage in more complex, long and difficult negotiations." The "Bali Roadmap" - which laid out a framework for two years of dialogue on an accord to replace the Kyoto Protocol - followed intense 11-day talks that appeared several times to be on the verge of collapse, largely because of US resistance. But early Saturday, the Americans reversed opposition to the final sticking point: Demands by developing nations seeking technological and financial help from the rich in fighting global warming. South Africa, Papua New Guinea and others had boisterously criticized the US stance.