WASHINGTON — An unchecked flood of weapons out of Libya, including thousands of shoulder-fired anti-aircraft missiles, is providing new firepower to Al-Qaeda-linked militias across northern Africa, according to Defense Department officials, accelerating conflict and raising new risks for US and western interests. There has been a continuing flow of weaponry since the fall of Libyan strongman Muammar Gaddafi in October 2011, said outside experts and Pentagon defense officials. The weapons include small arms, anti-tank mines, rocket-propelled grenade launchers, light machine guns, crates of ammunition and rockets, truck-mounted heavy machine guns, anti-aircraft artillery and Russian-made Strela anti-aircraft missiles. As a result, senior military officers say they are bracing for a long, persistent new campaign against the militias clustered around the Al-Qaeda offshoot called Al-Qaeda in the Islamic Maghreb (AQIM), which has absorbed most of the weapons spreading across Mali, Niger and northern Nigeria. US officials say they believe AQIM is actively engaged in equipping and training the militias across North Africa. “I see a greater risk of regional instability if we do not engage aggressively,” Army Gen. David Rodriguez told the Senate Armed SErvices Committee last week as it weighed his nomination to lead the US Africa Command. He said AFRICOM's intent is “neutralizing Al-Qaeda networks in Africa” with “greater engagements” in Libya, Niger, Tunisia, Algeria, Mauritania, Nigeria, Mali, Cameroon, South Sudan and Kenya. Arms looted from Libyan depots or sold by fleeing Gaddafi loyalists make up the bulk of the weapons that are being transported across Libya's poorly guarded borders. But an investigation by Conflict Armament Research, a British arms monitoring and analysis firm, also found that ammunition manufactured in Iran was intercepted last May in western Niger. A shipment of similar Iranian-manufactured ammunition was seized in northern Niger in 2011 after a skirmish with an AQIM militia, the firm reported. Bruce Hoffman, director of the Center for Security Studies and professor at Georgetown University's Edmund A. Walsh School of Foreign Service, says Al-Qaeda is not dead. Rather, he said it is spreading in Africa. “Conditions in that part of Africa, North Africa, are not entirely dissimilar to Iraq after the US invasion in 2003, with lots of different militias and armed groups feeding off of vast arms stockpiles,” Hoffman said. The Al Qaeda-linked militias “are armed almost to the extent of a small army — we're not talking about yesterday's terrorist with an AK-47 and a knapsack. Look what they're carrying away from Libya — heavy machine guns, heavy mortars, plastic explosives are the accoutrements of a small army.” Defense officials at the Pentagon expressed frustration at having an incomplete picture of where the arms are going. One official, discussing the shoulder-fired anti-aircraft missiles known as MANPADS, for Man-Portable Air Defense Systems, said “there are thousands of them” flowing out of Libya. Some of the MANPADS looted from Libya were Stela-2, or SA-7a weapons first fielded by the Red Army in 1968. More sophisticated versions, including Stela-3 missiles and the Igla-1, or SA-16, had also been provided to Libya. But after years in storage, it's not clear what effect dust and humidity had on the weapons' delicate electronic tracking systems and whether the batteries are still functional — or even whether the complete sets of launcher and missile survived intact. — Agencies