NAIROBI - A U.S.-trained Kenyan bomb disposal technician stood in a field showing colleagues from more than 20 countries how to collect evidence after the detonation of a roadside explosive.

Security experts who met in the Kenyan capital Nairobi this week say African nations must do more of such intelligence-sharing to counter weapons widely considered the greatest threat to their security forces: improvised explosive devices (IEDs).

Popularized by insurgents in Iraq and Afghanistan, homemade bombs were deployed by militants in nine African countries last year and killed about 3,600 people, according to U.S. Defense Department figures.

Some groups now use the weapons in complex attacks targeting civilians, including in January when a suicide bomber and gunmen from Somalia-based al Shabaab stormed an office and hotel complex in Nairobi, killing 21 people.

African officials at this week's meeting, organized by the U.S. military, acknowledged IEDs pose a major challenge to their forces, in part because the devices are constantly evolving as are the militant groups who use them.

"The enemy adapts faster than we react," said a Western official at the conference who asked not to be identified.

'Common enemy'

Training for Africa's police and military forces has typically focused on ways to avoid and defuse IEDs.

Now governments are looking to the next step: attacking networks that deploy them. This requires new skills, including analyzing remnants of a bomb to glean information about who made it and how it works.

But acquiring that intelligence is only half the battle, U.S. military and FBI experts told the conference. Ensuring it is disseminated throughout national security agencies and shared with counterparts in other countries is the other half.

Groups such as al Shabaab and Nigeria-based Boko Haram launch attacks in multiple countries, they reminded the conference.

"Unless intelligence is being shared at the appropriate levels and in a timely way, we'll never get ahead of the curve in dismantling these networks," said Matt Bryden, director of Sahan Research, a Nairobi-based think tank.

The amount of cooperation between security agencies varies in Africa, said Michael Solis, who helps lead counter-IED programs at the U.S. Africa Command.

"It is still a very nascent concept to share information," he added. "We had the same evolution in the U.S. ... We went through it decades ago, and now we have an effective multi-agency security sector."

Kenya, which is improving its bomb squad with training and support from the United States and other Western nations, is further ahead than most, U.S. experts said.

"It's essential for the military and the police to work together, so that we can win the battle against the common enemy," said Patrick Ogina, senior superintendent of the Kenyan police and deputy head of its bomb disposal unit.