BAMAKO– A French ground offensive in the town of Diabaly entered a fourth day Friday as diplomats said Mali’s Islamist rebels were better-equipped than expected. "Our enemies were well-armed, well-equipped, well-trained and determined,” a French envoy said. French troops’ initial clashes with Islamist militants in Mali have shown that the desert fighters are better trained and equipped than France had anticipated before last week’s military intervention, French and other U.N. diplomats said.The realization that the fighting could be bloodier than anticipated in the weeks—or months—ahead might make Western countries even more reluctant to get involved alongside France. French officials, however, hope it will rally their allies behind them, diplomats say."The cost of failure in Mali would be high for everyone, not just the people of Mali,” an African diplomat said on Thursday. Like the other diplomats, he spoke on condition of anonymity to discuss sensitive military and diplomatic issues.The seizure of dozens of hostages in neighboring Algeria, where Algerian troops launched a military operation to rescue the captives from "diehard” Islamist militants at a desert gas plant, also raises the possibility that Islamist violence could snowball beyond Mali’s borders.The diplomats were speaking after French forces had their first encounters with Islamist fighters in recent days. The ground war appeared headed for escalation on Thursday as French troops surrounded the town of Diabaly, trapping rebels who had seized it three days ago."Our enemies were well-armed, well-equipped, well-trained and determined,” a senior French diplomat said."The first surprise was that some of them are holding the ground,” he said, adding that others had fled during six days of French air strikes aimed at halting the militants’ offensive and preventing the fall of Mali’s capital, Bamako.