"Sticky bombs" have become the weapon of choice for the Taliban during a campaign of assassinations that swept across Afghanistan over the past year.
The US military revived the term "sticky bomb", which was used to describe its original low-tech cousin, the ST grenade, after encounters with the remotely detonated device during the 2003 invasion of Iraq.
ST grenades, used during the Second World War, had a casing that would fall away to expose a sticky area so the device could be attached to a tank. Use of the weapon was eventually abandoned after some grenades stuck to the user, with lethal consequences.
Relatively small, portable and light, the modern equivalent of these bombs have been used to kill thousands of government officials, security personnel, journalists, activists and civilians in Afghanistan since 2001.
Two Afghan soldiers, two police officers and a woman were killed on Saturday in Kabul, with Afghan and US officials blaming the Taliban for the attacks.
The Taliban have not claimed responsibility for the killings.
Making one or more people travelling in a vehicle the targets for attacks is a departure from the mass casualty-style suicide attacks that killed civilian in the past.
But the proliferation of sticky bombs in Afghanistan has led to an increase in so-called targeted killings, while the number of civilian casualties – although down in 2020 from the year before – surged.
This has worsened since intra-Afghan talks began and became deadlocked in September, a UN report said on Tuesday.
Afghanistan remains one of the world's deadliest places for civilians, the UN said.
"One belief that I and many other analysts share, is that the Taliban have been trying to remain as active as possible and carry out as much violence as possible, but at a lower threshold, which might still permit them to convince the Americans that they're engaging with the peace process that's supposed to be initiated," International Crisis Group's senior analyst on Afghanistan, Andrew Watkins, told The National.
He said that suicide bombings have not entirely "gone away" in the country. But the Taliban have acknowledged that they favour the use of sticky bombs.
In 2012, Qari Yousef Ahmadi was quoted as saying the group used the bombs in the "right situations".
He also said that the Taliban had the know-how to manufacture the devices.
“Evidence from arrests, raids and seizures by Afghan security forces shows that these devices are being assembled and manufactured in the country,” Mr Watkins said.
But the bombs could be sent to the insurgents from outside the country, he said.
"Many suspect that they came from Pakistan and the historical trend of Pakistan's state support to the Taliban in a variety of ways. Now, some point to Iran as a supplier of low-tech, small-scale weaponry to the Taliban or certain elements of the Taliban," he said.
The Taliban uses several tactics to not only smuggle equipment through checkpoints, but conduct surveillance and reconnaissance operations. One of the tactics involves using children.
"Underage children are used to spot vehicles, track licence plates, or carry the smaller devices into certain areas. No one at a check point is checking children's book bags," Mr Watkins said.
The frequency of sticky bomb attacks is causing fear throughout Afghanistan.
"After breakfast, I take a few minutes to think which route I should take to work to stay alive. The fear is intense," Rahmatullah Rahim, a bureaucrat in the Ministry of Justice, told Reuters in December.