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 / Updated By Ken Dilanian and Courtney Kube 
 
 WASHINGTON — A senior congressional aide who has been briefed on the deaths of four U.S. servicemen in Niger says the ambush by militants stemmed in part from a "massive intelligence failure." 
 
 The Pentagon has said that 40 to 50 militants ambushed a 12-man U.S. force in Niger on Oct. 4, killing four and wounding two. The U.S. patrol was seen as routine and had been carried out nearly 30 times in the six months before the attack, the Pentagon has reported. 
 
 The aide, who spoke on condition of anonymity because he is not authorized to speak publicly, said the House and Senate armed services committees have questions about the scope of the U.S. mission in Niger, and whether the Pentagon is properly supporting the troops on the ground there. 
 
 There was no U.S. overhead surveillance of the mission, he said, and no American quick-reaction force available to rescue the troops if things went wrong. If it weren't for the arrival of French fighter jets, he said, things could have been much worse for the Americans. 
 
 Congress also has many unanswered questions about what happened, he said, including about the specifics of the mission that day and the accounts lawmakers have been given about the timeline of the attack and rescue. 
 
 The aide said questions are being asked about whether the U.S. soldiers were intentionally delayed in the village they were visiting. He said they began pursuing some men on motorcycles, who lured them into a complex ambush. The enemy force had "technical" vehicles — light, improvised military vehicles — and rocket-propelled grenades, the official said. 
 
 After the rescue when it became clear that one soldier was missing, "movements and actions to try and find him and bring him back were considered. They just were not postured properly [to get him]." The body of Sgt. La David Johnson was not recovered until nearly 48 hours after the Oct. 4 attack. 
 
 A Pentagon spokesperson called the claim of an intelligence failure "speculation." 
 
 "An investigation is underway," said the spokesperson. "At the conclusion of the investigation, we will provide further details." 
 
 On Thursday, Director of the Joint Chiefs of Staff Lt. Gen. Kenneth McKenzie said that "every tactical engagement doesn’t necessarily proceed from an intelligence failure. We'll look at it and we'll come to conclusions about how intelligence could have supported adequately or inadequately the engagement that occurred. But on a battlefield, the enemy gets a vote." 
 
 "Sub-Saharan Africa is a very difficult place to operate," said Gen. McKenzie. 
 
 On Friday afternoon, Defense Secretary James Mattis met with Sen. John McCain, R-Ariz., chairman of the Senate Armed Services Committee, to discuss the Niger raid. 
 
 Earlier this week, McCain said the committee had not been provided with the information about the Niger mission that it "deserves." 
 
 Myeshia Johnson cries over the casket of her husband, Sgt. La David Johnson, who was killed in an ambush in Niger, upon his body's arrival in Miami, on Oct. 17, 2017. WPLG / AP 
 
 Sen. Lindsay Graham, R-S.C., told reporters Friday that it's too early to say whether there was an intelligence failure, "but that's exactly the kind of questions we should be asking ourselves." 
 
 He said Congress will require more information from a Trump administration that is expanding counterterrorism operations across the globe. 
 
 Trump is loosening the rules of engagement when it comes to lethal action against terrorists, and expanding the counterterrorism fight to different parts of the world, including across Africa, Graham said. 
 
 "The war is morphing," he said. "You're going to see more actions in Africa, not less." 
 
 In that context, Graham said, "I will insist that Congress is informed more often and in more detail," about military operations. 
 
 He added, "As the war expands, as the military had more authority, Congress is going to require more information." 
 
 Pentagon officials say operations in the region have already "tightened up" and there's been an operational "pause" while the U.S. military's Africa Command (AFRICOM) assesses the situation. U.S. officials believe the attack was carried out by a local terror group that claims association with ISIS. 
 
 Gen. Thomas Waldhauser, commander of AFRICOM since 2016, told Congress in March that only 20 to 30 percent of AFRICOM's needs for "intelligence, surveillance and reconnaissance" flights were being met. The Marine Corps general said there weren't enough helicopters to find wounded or dead soldiers, and that African partners weren't able to help with recovery missions. 
 
 "For personnel recovery," he said, "Africa Command relies heavily on contract search and rescue assets." ||||| PENTAGON -- Details of the ambush in Niger are slowly emerging more than three weeks after four U.S. soldiers were killed. The Americans were part of a larger group looking for an Islamic militant, but his fighters found them first. 
 
 The patrol that was ambushed was tracking a terrorist, Adnan Abu Walid al Sahraoui, the leader of an Islamic State of Iraq and Syria (ISIS) offshoot that operates in western Niger. 
 
 On Thursday, the Pentagon acknowledged for the first time that there was a second team of U.S. and Nigerien forces was on the ground. 
 
 Lt. Gen. Frank McKenzie briefs reports on the ambush in Niger that killed 4 Americans. CBS News 
 
 "There was one that had something to do with this operation but I'm not going to be able to give you any more specific details about what happened until we complete the process of the investigation," said Lt. Gen. Frank McKenzie. 
 
 CBS News has learned that the second team was on a kill or capture mission for al Sahraoui. But it was called off after he slipped across the border into Mali. 
 
 ISIS offshoot likely connected to Niger ambush 
 
 Instead, the patrol with 12 Americans and 30 Nigeriens was told to investigate an area where the terrorist had been. The patrol was also told not to expect enemy contact. 
 
 After gathering intelligence, the men stopped in the village of Tongo Tongo. They were ambused by al Sahraoui's fighters as they left. Sources say the U.S. team did immediately alert their commanders they were taking fire. But the patrol waited an hour before asking for help. 
 
 French special operations forces were among the first to respond to the U.S. call for help during an ambush in Niger. CBS News 
 
 "You know, we look at that hour pretty hard ourselves, but again there are a lot of reasons why that time could've elapsed like that," McKenzie said. 
 
 Investigators still do not know how Sgt. La David Johnson got separated from the other soldiers during the attack. His body was recovered two days later. 
 
 CBS News learned on Thursday that a French special operations team was the first ground force to respond to the call for help from troops from the U.S.-Nigerien patrol when they were attacked on Oct. 4. The French team was on the scene within 3-4 hours of the call, after the French military sent jets from Niger's capital, Niamey, and Mali, a source said. 
 
 The U.S. military is still unsure how Army Sgt. La David Johnson became separated from forces on the ground in Niger. CBS News 
 
 Military officials briefed members of Congress Thursday. Democrat Richard Blumental said he had questions about the mission of the roughly 6,000 U.S. troops stationed in Africa. 
 
 "One of the reasons for this tragic catastrophe in Niger may well have been lacking resources in intelligence that could have permitted them to avoid that ambush," Blumenthal told CBS News. ||||| NIAMEY (Reuters) - French and Nigerien troops were conducting operations on Thursday in a region of Niger where three U.S. Army Special Forces members were killed the day before, becoming the first American soldiers to die in West Africa in decades. 
 
 Three Nigerien soldiers were also killed and two U.S. soldiers wounded in the attack, which took place in a southwestern Niger region where insurgents are active, U.S. Africa Command spokeswoman Robyn Mack said. 
 
 France’s regional Barkhane force was asked to support a counterattack after the Niger and U.S. troops were ambushed, French army spokesman Colonel Patrick Steiger told a news conference in Paris. 
 
 “It’s not clear if the attackers knew the Americans were present,” said a Western security source. “Initial information suggests there was a trap that appeared designed to get them out of their vehicles and then they opened fire.” 
 
 Insurgents in the area include militants from al Qaeda in Islamic Maghreb and a local branch of Islamic State, Mack said. The Western security source said al Qaeda and a relatively new group called Islamic State in the Greater Sahara were the main suspects, although no one had yet claimed responsibility. 
 
 Two other Niger security sources said four military helicopters had been sent to the region and that reinforcements arrived on Thursday morning in the Tillaberi area, where the attack took place. 
 
 The Pentagon declined to discuss details, citing ongoing operations, but said the U.S. forces were part of a growing mission to bolster Niger’s armed forces’ ability to battle militants. 
 
 “We extend our deepest condolences and sympathies to the families of the fallen, and those injured in this attack,” Pentagon spokeswoman Dana White told a news briefing. 
 
 AMBUSH 
 
 Nigerien army Colonel Abou Tagué said the joint Nigerian-American patrol on the Mali-Niger border was ambushed by militants riding “in a dozen vehicles and about 20 motorcycles near the village of Tongo Tongo.” 
 
 He cited intense fighting, saying the joint Nigerian-American force “showed courage.” He said four Nigerien soldiers were killed and eight were wounded. 
 
 A statement by U.S. Africa Command on Thursday said one unspecified “partner nation member” had died but did not name the nation. 
 
 In a speech on Thursday, Niger President Mahamadou Issoufou condemned the attack. “Our country has just been the victim of a terrorist attack that claimed a large number of victims,” he said. 
 
 Islamist militants form part of a regional insurgency in the poor, sparsely populated deserts of West Africa’s Sahel. Jihadists have stepped up attacks on U.N. peacekeepers, Malian soldiers and civilian targets since being driven back in northern Mali by a French-led military intervention in 2013. 
 
 Malian militant groups have expanded their reach into neighboring countries, including Niger, where a series of attacks by armed groups led the government in March to declare a state of emergency in the southwest. 
 
 The European Union has pledged tens of millions of euros to a new regional force of five Sahelian countries - Niger, Mali, Chad, Burkina Faso and Mauritania - in a bid to contain Islamist militant groups. The United States also views the region as a growing priority. 
 
 Rinaldo Depagne, West Africa project director at International Crisis Group, said the borderlands between Mali, Niger and Burkina Faso were “becoming a new permanent hotbed of violence”, threatened by increasingly organized militant groups. 
 
 “This shows the level of organization of these groups and also their confidence,” Depagne said. 
 
 Andrew Lebovich, a visiting fellow at the European Council on Foreign Relations, said Wednesday’s attack revealed how U.S. training of Nigerien forces “has accelerated and also verged into ongoing military operations”. 
 
 The United States has about 800 service members in Niger, where it operates surveillance drones out of a $100 million base in the central city of Agadez to support the country’s efforts to combat jihadists and protect its porous borders. 
 
 It has also sent troops to supply intelligence and other assistance to a multinational force battling the Nigerian Boko Haram militants near Niger’s border with Nigeria.
– Confusion around the attack that left four US soldiers dead in Niger earlier this month continues, with the Pentagon investigating whether the soldiers had left a routine patrol to chase insurgents without the proper approval, the New York Times reports. US soldiers say they "noticed" insurgents in the area while conducting a patrol—one the Pentagon says the team has conducted nearly 30 times in the past six months, according to NBC News—but did not chase them. US soldiers say the insurgents later ambushed them. But Nigerien military officials say the team, which included Nigerien soldiers, chased the insurgents across the Mali border only to be ambushed on their way back. A mission to go after insurgents would have required approval from higher-ups and would complicate the Pentagon's claim that the US isn't involved in combat operations in Niger. The conflicting accounts given by US soldiers and the Nigerien military are just one more question surrounding the Oct. 4 attack, questions that include information as basic as what US troops are doing in a remote corner of Niger in the first place. A senior congressional aide briefed on the attack says the whole thing represents a "massive intelligence failure." The aide says the mission was being carried out without any overhead surveillance and without a "quick-reaction force" to step in if things went bad, which they did. He says the attack could have been much worse if French fighter jets hadn't shown up. A Pentagon spokesperson says any talk of intelligence failure is "speculation" while an investigation is still underway. Meanwhile, Al Jazeera reports at least 12 Nigerien troops were killed by insurgents in an attack Saturday along the same border with Mali.