Fifteen years ago, when I returned home after fighting in Iraq, a friend asked me to describe the bravest thing I saw anyone do. I had led a Marine platoon in the Second Battle of Fallujah, in 2004, and had seen plenty of heroism--Marines dragging their wounded off machine-gun-swept streets, or fighting room to room to recover a comrade's body. But none of these compared to the cumulative heroism of the 19- and 20-year-old infantrymen who placed their bodies across that fatal funnel--a doorway with a potential enemy inside--every day. Clearing the enemy from the city, house by house, was a game of Russian roulette played on a grand scale. You never knew who might be waiting on the other side of the door.

The potential use of drones to cripple as much as half of Saudi national oil production this week highlights a growing threat in modern-day conflict. The attack has shown that Saudi Arabia -- the world's third largest defence spender -- is incapable of defending arguably its most protected non-military installation in Abqaiq. It is estimated to have halted around 5 per cent of international crude output, has shocked markets and spiked prices globally. Only a decade ago, such an attack by a low-cost, remote weapon systems was largely unthinkable. And players on the world stage have seized on the shift, with groups such as Islamic State and Mexican drug cartels creating their own improvised explosive vehicles from rudimentary hobby kits purchased online and in stores.

When U.S. Special Forces entered Afghanistan in 2001, Facebook didn't exist, the iPhone had yet to be invented, and "A.I." often referred to an NBA star. Seventeen years later, American special operations forces continue to ride horseback in rural Afghanistan, but information technology has advanced rapidly. Recent breakthroughs in robotics and artificial intelligence (AI) have captured the popular imagination and prompted sober talk of an impending AI revolution. Yet surprisingly little of that talk has touched on the small wars and insurgencies that have dominated U.S. foreign policy in the 21st century. The definitive work on emerging technology and insurgency has yet to be written, but two recent books offer suggestions for how the era of big data and AI will affect the United States' modern conflicts.

Editor's Note: The rapid pace of technological innovation is changing the nature of warfare, and futurists are busy spinning out scenarios of a U.S.-China clash in twenty years involving nano-technology and fully autonomous weapons systems. Yet how will new technologies shape insurgency and counterinsurgency, which conjures up images of guerrillas hiding in Vietnam's jungles? My Brookings colleague Chris Meserole looks at two of the latest books on the subject and assesses how the balance between rebels and government may tilt. When U.S. Special Forces entered Afghanistan in 2001, Facebook didn't exist, the iPhone had yet to be invented, and "A.I." often referred to an NBA star. Seventeen years later, American special operations forces continue to ride horseback in rural Afghanistan, but information technology has advanced rapidly.

Nov. 7, 2013: Pakistani Taliban leader Mullah Fazlullah is seen on television at a coffee shop in Islamabad. The Pakistani Taliban leader known for beheading police officers and even ordering the assassination of Nobel Peace Prize winner Malala Yousafzai has been killed by a U.S. drone strike, Afghanistan's Defense Ministry says. Mohammad Radmanish told the Associated Press on Friday that Mullah Fazlullah, the ruthless insurgent leader, died along with two other terrorists a day earlier in the Marawara district along the Afghanistan-Pakistan border. A statement attributed to U.S. Forces-Afghanistan spokesman Lt. Col Martin O'Donnell said an American "counterterrorism strike" was carried out in the region targeting "a senior leader of a designated terrorist organization," but did not say whether it had killed anyone. Fazlullah previously ordered the bombing and beheadings of dozens of opponents when his band of insurgents controlled Pakistan's picturesque Swat Valley from 2007 until a massive military operation routed them in 2009.

WASHINGTON – Dramatic new drone video of the Niger ambush that killed four American soldiers shows U.S. forces desperately trying to escape and fighting for their lives after friendly Nigerien forces mistook them for the enemy. It describes how the fleeing troops set up a quick defensive location on the edge of a swamp and -- thinking they were soon to die -- wrote messages home to their loved ones. The video, released by the Pentagon with explanatory narration, includes more than 10 minutes of drone footage, file tape and animation that wasn't made public last week when the military released a portion of the final report on the October attack. The video depicts for the first time the harrowing hours as troops held off their enemy and waited for rescue. There were 46 U.S. and Nigerien troops out on the initial mission in the west African nation, going after but failing to find a high-value militant, then collecting intelligence at a site where the insurgent had been.

WASHINGTON – As bad as President Donald Trump describes U.S.-Pakistani ties today, they can get far worse. Over 16 years that included hundreds of deadly U.S. drone strikes, Osama bin Laden's killing on Pakistani soil and accusations Pakistan helps insurgents that kill Americans, the reluctant allies never reached one point of no return: Pakistan closing the air routes to Afghanistan. It could also be tantamount to Pakistan going to war with the United States. Even if such a step is seen as unlikely by most officials and observers, Pakistan's ability to shape the destiny of America's longest war is a reminder of how much leverage the country maintains at a time Trump is suspending hundreds of millions of dollars in military assistance. "There's some suggestion that we have all of the cards in our hands," said Richard Olson, a former U.S. ambassador to Pakistan.

More than 100 of the world's top robotics experts wrote a letter to the United Nations recently calling for a ban on the development of "killer robots" and warning of a new arms race. But are their fears really justified? Entire regiments of unmanned tanks; drones that can spot an insurgent in a crowd of civilians; and weapons controlled by computerised "brains" that learn like we do, are all among the "smart" tech being unleashed by an arms industry many believe is now entering a "third revolution in warfare". "In every sphere of the battlefield - in the air, on the sea, under the sea or on the land - the military around the world are now demonstrating prototype autonomous weapons," says Toby Walsh, professor of artificial intelligence at Sydney's New South Wales University. "New technologies like deep learning are helping drive this revolution. The tech space is clearly leading the charge, and the military is playing catch-up."

Faced with an enemy fighter jet, there's one sensible thing a military drone should do: split. But in December 2002, caught in the crosshairs of an Iraqi MiG, an unmanned US Predator was instructed to stay put. The MiG fired, the Predator fired back and the result, unhappily for the US, was a heap of drone parts on the southern Iraqi desert. This incident is often regarded as the first dogfight between a drone, properly known as an unmanned aerial vehicle or UAV, and a conventional, manned fighter. Yet in a way, the Predator hardly stood a chance.

The US has confirmed the death of a senior al-Qaeda leader targeted by a US drone strike in north eastern Afghanistan last month. Farouq al-Qahtani, the group's leader in the area, was killed two weeks ago in what the Pentagon described as a precision strike. Saudi-born al-Qahtani was placed on a US list of most wanted terrorists in February. He was said to be one of al-Qaeda's senior plotters against the US. Saudi-born al-Qahtani, a Qatari national, was also accused of involvement in plots targeting Europe.