Between 1997 and 2000, and using Tajikistan's remote mountainous areas as its base, the IMU carried out kidnappings, assassinations, and a series of armed raids deep into Kyrgyzstan and Uzbekistan. Its stated objective: to establish an Islamic state in Uzbekistan.
The IMU then relocated its base of operations to Afghanistan and extended its mandate. It now wanted to overthrow all regional Central Asian governments. At the time, intelligence sources put its membership at some 3,000-4,000 militants. It has now been two years since the IMU was believed to have been largely destroyed by the U.S.-led military campaign that toppled Afghanistan's Taliban regime. Does it remain a threat to Central Asian security?
Regional security expert Ahmed Rashid, the author of "Jihad: The Rise of Militant Islam in Central Asia," tells RFE/RL the IMU could regain strength -- but as a political force rather than a military one. "The IMU has always remained a presence in Central Asia. At the end of the war with the Taliban, the military force of the IMU, which was based in Afghanistan, was clearly wiped out. But some of them have escaped to the Pakistan border, where they've been living. But I think the real threat has always been the IMU's underground network inside Central Asia. And that really has not been broken. Maybe they don't have money [or] weapons; maybe they're not even properly organized because of the lack of leadership. But I think you could get a revival of such forces," Rashid said.
The IMU's military leader, Juma Namangani, is believed to have been killed in northern Afghanistan. But Rashid said it is widely assumed that the group's political leader, Takhir Yuldashev, is hiding in the tribal belt along the Afghan-Pakistani border.
The U.S. State Department released this week a public announcement for Tajikistan, warning that terrorist groups allied with Al-Qaeda, such as the IMU -- which is featured on the U.S. blacklist of terrorist groups -- remain "active" in the country and still pose "risks" to travelers.
Last year, the State Department issued advisories for Uzbekistan and Kyrgyzstan, warning that radical organizations like the IMU could be planning attacks targeting U.S. interests.
But Tajik Deputy Prime Minister Saidamir Zuhurov has said there is no information available indicating the IMU has stepped up its activities in Tajikistan.
Nuralisho Nazarov, head of the Tajik border guards staff, last year repeatedly told RFE/RL correspondents that terrorist groups continued to be present on the Afghan side of the border with Tajikistan. He said these groups could easily reach any region of Tajikistan.
Amirkul Azimov, head of Tajikistan's Security Council, over the past several months had strongly denied the presence of terrorist groups at the border threatening Tajik security. But in an interview this week with RFE/RL, he neither confirmed nor denied the reports. "In any case, the presence of any terrorist group in this particular region or any other region is a serious threat. Particularly, the presence of the IMU at the Tajik-Afghan border is a serious threat to Tajikistan and the whole of Central Asia," Azimov said.
Azimov cautiously stressed that his country is able to take any measures needed to deal with this terrorist group in order to provide security in the country.
Colonel Talant Razzakov is an official with Kyrgyzstan's National Security Service. He says, "Of course, there is a danger of IMU for Kyrgyzstan because the Taliban movement has not been fully crushed yet. They are continuing their struggle using both military force and ideological means in Pakistan and the border areas near Pakistan."
In Kyrgyzstan and Uzbekistan, alleged members of the IMU were detained last year for their suspected involvement in explosions in Bishkek and Osh in 2002 and 2003.
But analysts remain unconvinced about the IMU's military threat. Rashid says militant groups have always been present in northern Afghanistan. But he notes that U.S. pressure there is now so strong that it will be very difficult for these groups to resume a strong military presence.
David Lewis is head of the International Crisis Group's Central Asia project in Osh, in southern Kyrgyzstan. He says the IMU's activities in Central Asia have been exaggerated.
"There is some evidence that small groups of people linked to the IMU have tried to enter Central Asia or reactivate their activities. This all remains small-scale and rather unorganized. I think in some way their activities have always been exaggerated. It's been useful for some of the governments in Central Asia to have a threat and it's been one of the reasons for the kind of repression we've seen in Uzbekistan and the strong role of security forces throughout the region," Lewis said.
Lewis notes that it is hard to tell whether the IMU represents a proper organized force or an alliance of small groups. He says some members seem to have been recruited by drug traffickers and other criminal groups, while others have moved on to part of the global Islamic movement in Afghanistan and Pakistan.
Analysts underscore that much of the religious extremism in Central Asia is fueled by the radicalization of politics rather than by political Islam.
Rashid says local political systems need to open up in order to prevent extremist Islamic groups from developing in Central Asia.
"The enormous repression of the regimes and the lack of any kind of political expression naturally forces politically oriented people to go underground and to become radicalized, and then join these Islamist groups," Rashid said.
While the IMU's capacity for future action remains dubious, attention in Central Asia has refocused on Hizb ut-Tahrir, which experts estimate has up to 20,000 members in the region. The group, which seeks the establishment of a caliphate in the region, is banned in all Central Asian states.
Hizb ut-Tahrir has always defended what it calls a staunch commitment to nonviolence. But Uzbek intelligence officers argue that although Hizb ut-Tahrir members have not advocated violent means in the past, they could easily turn in that direction.
(Sojida Djakhfarova from RFE/RL's Tajik Service and Tyntchtykbek Tchoroev, director of RFE/RL's Kyrgyz Service, contributed to this report.)