Improvised explosive devices, as the military calls them, have been the largest killer of American forces in Iraq and Afghanistan, showing up with devastating effect in Pakistan and India, but also with less notice in Thailand, Sri Lanka, the Philippines, Colombia, Somalia and parts of North Africa.
Even Russian security forces have faced the devices in the republics of Ingushetia and Dagestan, although attacks in Chechnya have fallen.
“There is a robust and constant I.E.D. effort among violent extremists who are using it as their weapon of choice,” said Lt. Gen. Thomas F. Metz, director of the Pentagon’s organization in charge of seeking ways to counter improvised explosives. “That won’t change for decades. We are in this fight for a long time.”
General Metz, who will discuss the spread of improvised bombs during testimony on Thursday before a House Armed Services subcommittee, said global I.E.D. cases outside Iraq and Afghanistan averaged about 300 per month. The count includes detonations and the discovery of intact devices. The military’s global statistics on the bombs remain classified, to prevent extremists from knowing what the United States knows. But a compilation of worldwide episodes from private-sector security consultants illustrates the threat.
Jonathan M. George, of HMS Inc., a private company that analyzes the use of improvised explosive devices and consults on countermeasures, maintains a database on cases, gathered from public documents and news reports, that military officers consider reliable enough to cite in public statements.
Mr. George said the count of improvised bombs in Afghanistan had grown from 515 in 2006 to 705 in 2007, 828 in 2008 and 955 so far this year. In Iraq, the annual figures show the count has diminished, from 4,718 in 2006 to 3,275 in 2007, 3,253 in 2008 and 1,135 so far this year.
But his compilation also tracks the larger number of I.E.D.’s that explode or are found in the rest of the world: 3,267 in 2006, 4,027 in 2007, 4,273 in 2008 and 2,121 so far in 2009.
“Recent events show that although the number of I.E.D. attacks has fallen, the number of high-casualty and high-profile attacks continue to rise,” he said.
He said that Pakistan had experienced the worst problem after a rise that began in 2007, after the Pakistani military mounted an eight-day siege to end a standoff that lasted for months with Islamic extremists holed up at the Red Mosque in Islamabad. India has the second-highest number of I.E.D.’s, and the level there remains constant, Mr. George said. Thailand is third, but the number has decreased following a peak in 2007.
Extremists are not only increasing the power of their devices but also showing a grim cleverness in the delivery systems. Raids on a Tamil Tigers base in Sri Lanka uncovered an experimental, remotely controlled boat that could be loaded with explosives to slip alongside the hull of a ship for detonation.
Other American military officers say that the improvised bombs are being studied as a military tool by some state powers.
The senior American commander in South Korea, Gen. Walter L. Sharp, said that the North Koreans were studying the weapons and their uses.
“We started to work very hard, to make sure we’re learning the lessons out of Iraq and Afghanistan with I.E.D.’s and other types of devices,” General Sharp said in Washington last month.
Then, in referring to the North Korean government, he added, “I’m pretty confident that they have learned” from observing how insurgents used devices in Iraq and Afghanistan. The American military now believes that North Korean special operations forces are training to use improvised explosives.
“I’m confident they will use those capabilities,” General Sharp said. “So we’re working very hard on that now.”
He did not elaborate on how North Korea might employ the bombs. But other American government officials, speaking on the condition of anonymity, described the assessments: While conflict with the North appears remote, the United States and South Koreans anticipate that if war breaks out, North Korean conventional forces will plant I.E.D.’s to maul any allied advance from south to north, and that North Korean commandos will try to infiltrate the south to plant them along major roadways to wound and kill civilians and allied troops.
Senior military officers confirm that American and South Korean forces on the peninsula are now incorporating countermeasures in updated war plans and practicing them in war games.
General Metz, who will retire from the military in the coming weeks, acknowledged that while the public had focused on the threat that the bombs posed to American forces in Iraq and Afghanistan, part of his reason for describing the risk of spreading improvised bombs was to argue for continued financing for his organization’s work on countering them.
“What the American people do not realize is that this weapon of choice by violent extremists is being used for strategic purposes,” he said. “The United States cannot be beaten tactically by the I.E.D. — but strategically, these extremists hope to wear down our will.”