U.N. peacekeeping forces lack the troops and equipment necessary to improve the situation in violence-wracked Darfur and will continue to be ineffective until mid-2008, the U.N. peacekeeping chief cautioned Wednesday. United Nations officials are discussing with Ukraine and Russia ways of obtaining helicopters and other equipment while also considering pulling them away from other U.N. peacekeeping missions, said Jean-Marie Guehenno, the U.N. undersecretary-general for peacekeeping. Guehenno's warnings of "dire consequences" for Sudan, during a half-hour report to U.N. Security Council members, raised questions about whether the African Union-United Nations peacekeeeping mission that took over just this month can provide even for its own security. In his assessment, Guehenno offered a grim outline of the council's options and the many political and bureaucratic obstacles they face. The beleaguered A.U.-U.N. mission, as the latest international effort to quell the widespread violence in western Sudan, has 9,000 soldiers and police officers, but it is supposed to have 26,000. "We do not yet have guaranteed agreements from the (Sudanese) government on basic technical issues," Guehenno told the council. "The mission itself will not have the personnel or assets in place to implement its mandate for many months, even in the best-case scenario." "There is no good reason that these issues should persist ad infinitum," Guehenno said. "It is clear that these deployments must move more quickly if we are to have a material impact on the situation in the first half of this year." Guehenno, a former French ambassador and career diplomat, also told reporters that Darfur poses "the greatest risk for the United Nations" in a decade. U.N. Secretary-General Ban Ki-moon on Wednesday reproached Sudan for its soldiers firing two days earlier on a U.N. convoy of more than 20 "clearly marked" vehicles protected by South African peacekeepers, who did not return fire, according to U.N. spokeswoman Michele Montas. The convoy carried Russian personnel to western Darfur; a Sudanese driver suffered seven gunshot wounds. Ban insisted Sudan now "has to provide unequivocal guarantees" it will not risk another such incident, his spokeswoman, Michele Montas, said.