ISLAMABAD (AFP/Reuters) - The United States is working to avoid mistakes that allowed vanquished Taliban in Afghanistan to escape into Pakistan and mastermind a deadly insurgency, the regional envoy said Thursday. Well continue to come back very regularly to improve coordination. That was not (the case) in 2002 and that was grievous mistake, Richard Holbrooke, US special representative for Afghanistan and Pakistan, told journalists before leaving for Afghanistan at the end of two days of talks with the Pakistani political and military leadership in Islamabad. Thousands of Taliban and al Qaeda fighters fled to Pakistans tribal lands to escape the onslaught of US backed forces in late 2001 Hunkered down in remote territory outside direct government control, the militants regrouped, directed attacks against Western troops in Afghanistan and nourished an insurgency that has since reached record levels. On July 2, the US military launched one of its biggest offensives in Afghanistan, flying 4,000 US Marines into battle against Taliban in southern province of Helmand ahead of presidential elections on August 20. Pakistani officials have expressed concern that the US military action will force militants into Pakistan and further inflame the troubled region of Balochistan, which borders Helmand. Pakistan has also moved forces to Balochistan, to patrol the southwest provinces border with Helmand, the southern Afghan province where US forces began an operation against the Taliban earlier this month. Holbrooke stressed that there was increasingly tight cooperation between the Pakistani and US and NATO forces. He also said there was little evidence that Taliban fighters had fled from Helmand to Pakistan, but he had still to discover how the guerrillas had melted away. So far they havent really showed up, but we want to avoid the mistake of 2002 when US offensives ignored the consequences in Pakistan, Holbrooke said. A key thing is the coordination between the Afghan army and Pakistani army, said Holbrooke, adding that this time there is coordination. Holbrooke hailed Thursday the return home of many of the 2.5 million people displaced by fighting in Swat valley despite pockets of Taliban resistance. Holbrooke described securing valleys, where the Pakistan army opened up an offensive against the militants more than three months ago, as the first priority. I think theyve got their hands full in Swat and Buner, he told journalists. The US envoy said this was the likely reason why the army was delaying an all-out assault further west against the stronghold of Taliban commander Baitullah Mehsud in the remote South Waziristan tribal region. Theyve got to make sure when the refugees come back that they have security, so maybe theyre delaying the offensive, he said, adding that he did not know the timing or nature of the looming action against Mehsud. The United Nations said on Thursday nearly 400,000 people had returned home from the camps and makeshift shelters. Theyre returning in large numbers, thousands a day, and I think that is good news, he said. Holbrooke spoke of the heavy US financial assistance for Pakistans government, military and its displaced people, and said that he hoped to announce help for Pakistan to overcome crippling power generation shortages when he returned next month. The government gave orders to the army a month ago to go after Mehsud, who leads a loose grouping of some 13 Taliban factions dotted across the northwest. Mehsud has come under frequent air and artillery bombardment since then but there are few signs of an imminent ground assault on his redoubt in the mountains. The army is probably waiting to free up some of the 20,000 troops currently deployed in Swat, according to diplomats who follow military affairs. Although Mehsud has helped provide fighters for the Taliban insurgency in Afghanistan, and trained suicide bombers to attack Afghan and Western forces, most of his focus has been on attacking the Pakistani state. Several diplomats in Islamabad doubted whether eliminating Mehsud would provide any great strategic value for Western forces fighting the Taliban in Afghanistan, but Holbrooke disagreed. I think Baitullah Mehsud is one of the most dangerous and odious people in the region and the United States had paid insufficient attention to him until recently, he said. He said it made sense for the Pakistani government to first go after the militants, like Mehsud and Fazlullah, the Taliban commander in Swat, that posed a threat to their nation.