French to send 1,000 more troops to Mali; U.S. playing supporting role French soldiers from the 2nd Navy Infantry Regiment shortly after deplaning at an air base near Bamako, Mali, on Monday. By Richard Engel and Robert Windrem, NBC News France will send about 1,000 troops and armored vehicles to Mali over the next few days with the support of U.S military and intelligence operations, upping the ante in its effort to turn back Islamic militants threatening to topple the north African nation's government, U.S. national security officials told NBC News on Monday. French mechanized forces will join approximately 500 French troops already on the ground in the country, battling fighters from at least three Islamic militant groups, including al-Qaida in the Islamic Magreb (AQIM), according to the officials, who spoke on condition of anonymity. Al Qaeda-linked Islamist rebels in Mali have promised to drag France into an Afghanistan-style war. They've launched a counteroffensive after four days of French air strikes on their northern strongholds. There are reports the Islamists have seized control of Diabaly a town 250 miles north of the capital Bamako. Jonathan Miller Channel Four Europe reports. The military escalation follows intense bombardment over the weekend by French aircraft of Islamic militant positions in the country's north, where they effectively created an al-Qaida refuge late last year. The French force will be aided by U.S. military and intelligence operations, the officials said. The U.S. will provide both transport and refueling capability for the operation as well as intelligence, including drones, the officials added. The U.S. Africa command, headquartered in Djibouti in East Africa, is coordinating the U.S. operation, said the officials. The U.S. has been providing intelligence-gathering assistance - primarily spy satellites - to the French in their assault on Islamist extremists, which began with a series of aerial attacks that began on Friday and continued through Monday. But French Defense Minister Jean-Yves Le Drian told the Associated Press that the rebels fought back on Monday, overrunning the garrison town of Diabaly, about 100 miles north of Segou, the administrative capital of central Mali. French Mirage F1 CR fighter jets sit on the tarmac at a French air base near Bamako, Mali. France has been using the aircraft to pound hardline Islamist groups controlling northern Mali. Defense Secretary Leon Panetta and other U.S. officials told the AP early Monday that they would not rule out having American aircraft land in the West African nation as part of future efforts to lend airlift and logistical support. Separately, U.S. officials in Washington told NBC News that, while there are no current plans for the U.S. to provide direct combat support - American combat forces on the ground or aerial combat support from manned aircraft or unmanned drones - a small number of U.S. advisers could be tasked to work directly with French combat forces in non-combat roles. Speaking to reporters traveling with him to Europe, Panetta said that while AQIM, and other affiliate groups in Mali may not pose an immediate threat to the United States, "ultimately that remains their objective." For that reason, Panetta said, "We have to take steps now so that AQIM does not get that kind of traction." The U.S. officials say France's big fear is that if they don't eliminate AQIM and other allied Islamic militant groups in Mali, it will become a terrorist safe haven, as Afghanistan and Yemen have been at various times over the past 20 years. Mali is a lot closer to Europe than either of those countries. Moreover, there are 200,000 Malians living in France, most of them in and around Paris. AQIM and other groups could, it is feared, recruit supporters from within that community to launch terrorist attacks in France. France is not alone either, say the U.S. officials. Britain, Portugal and Spain fear AQIM attacks from Islamic militants in the Sahel region of North Africa as well. "The ease with which individuals can move from North Africa to Europe makes such attacks a real possibility and are clearly the principal motivation for French action," said Michael Leiter, former director of the National Counter Terrorism Center and now a consultant to NBC News. How did it begin? After U.S. and NATO forces helped topple Moammar Gadhafi in Libya, neighboring Mali imploded. First rebels in the north revolted, then the military carried out a coup against the government in Bamako. Amid the chaos, Islamic militants defeated breakaway rebels in northern Mali and last week began to advance on Bamako. That's when the military-led government asked France to intervene. On Monday the French continued bombing raids across Mali's north in an effort to root out fighters who seized control of a large chunk of the region starting nine months ago. French fighter jets bombed the airport, training camps, warehouses and other facilities used by the al-Qaida linked rebels. "In some ways, this has been a long time coming," said Leiter. The U.S. and France have been very focused on AQIM since at least ... 2006. ... Also, in 2007, its major attack on Algerian troops caused significant alarm in Washington and Paris, spurring significant investment in intelligence collection, cooperation and increased military and diplomatic efforts. The AQIM, a Sunni extremist group, was previously headquartered in Algeria, where Islamic militants clashed with the government in a bloody war during the 1990s. The Algerians responded aggressively and pushed AQIM south to the border area with Mali. Since 2008, the Obama administration has partnered with the French, whose deep roots in the region go back more than a century when the area was part of French West Africa. "The French had capacity that was hard to come by in D.C.," added Leiter. This path produced some useful gains, but the French were often caught up with their elections and the like. Why French are taking on Mali extremists In recent years, AQIM became "very much focused" on low-level kidnappings of Europeans in Africa, bringing in tens of millions of dollars in ransoms and giving it the ability to move quickly into the power vacuum in Mali. AQIM is one of several Islamic extremist groups that have set up shop in northern and western Africa. U.S. officials point to recent cooperation between AQIM and Boko Haram, an al-Qaida operation in northern Nigeria, as another troubling development that pushed U.S.-French cooperation. Roger Cressey, who worked as deputy director for counterterrorism at the National Security Council in both the Clinton administrations, said U.S. policy makers also are concerned that AQIM could form alliances with other groups. "Key for U.S. policy makers is to provide support to the French that is consistent with our specific and limited interests in West Africa," he said. The long- term concern has been that AQIM will interact with al-Shabab in Somalia and AQAP (al-Qaida on the Arab Peninsula) in Yemen and create a capability that threatens our interests beyond W Africa. Although AQIM's links with al-Qaida's core in Pakistan have never been "especially operationally tight," noted Leiter, "It isn't clear that it matters much now. AQIM is basically operating independently. So far, he added, AQIM has been very limited outside the region. Richard Engel is NBC News" Chief Foreign Correspondent; Robert Windrem is a Senior Investigative Producer; NBC News" Chief Pentagon Correspondent Jim Miklaszewski, Pentagon producer Courtney Kube and the Associated Press also contributed to this report.