Attackers dressed in paramilitary uniform killed 10 foreigners preparing to climb the world's ninth highest peak, Nanga Parbat (8,126m), in northern Pakistan.
Pakistanis awoke to the news of an unprecedented attack on mountain climbers in the Gilgit-Baltistan region, which has been trying to win back foreign tourists wary of visiting a country battling terrorism and insurgency.
The Pakistan Taliban have claimed responsibility for the attack, which occurred just after midnight Sunday local time.
Mountain tourism and expeditions are a major part of the local economy.
"This hits Pakistan where it hurts," said Imtiaz Gul, executive director of the Islamabad-based Centre for Research and Security Studies. "After several years, Pakistan was witnessing a resurgence of [mountain] expeditions to these areas. But now they [Pakistan Taliban] have delivered a most fatal blow," he added.
The victims included tourists from China, U.S., Ukraine, Slovakia, Lithuania, and Nepal, and a Pakistani guide. Their bodies were transported to Islamabad Sunday.
"No one would have thought about it that these guys would be coming over 4,000 meters to ambush a foreign expedition – so that makes it spectacular as well as extremely damaging," said Mr. Gul.
Pakistani government officials condemned the attack and ordered security agencies to find and arrest the perpetrators.
The killings have plunged the weeks-old government in to crisis over how to handle the Pakistan Taliban's increasingly brazen attacks.
The Tehrik-e-Taliban, or Pakistan Taliban, said it carried out Sunday's attack in retaliation for a U.S. drone strike that killed the group's number two, Waliur Rehman, in late May, shortly before the swearing-in of Pakistan prime minister Nawaz Sharif.
Following the drone strike, the Pakistan Taliban said it was withdrawing its offer of peace talks with the Pakistani government and vowed revenge.
In the run-up to the May election, Mr. Sharif said military force alone could not eliminate the terrorist threat and suggested that talking to the Pakistan Taliban ought to be an option.
The Nanga Parbat terrorist attack puts any future talks in to doubt.
"I only hope it clarifies [Nawaz Sharif's] thinking and takes away the confusion that has prevailed as to the nature of this threat and how it is trying to change the very nature and foundation of Pakistan," said security analyst and retired Pakistan army three-star general Talat Masood.
"To me there is hardly anything to negotiate when they [Pakistan Taliban] are coming with such kind of attacks," added Mr. Masood.
The Pakistan army has been waging a fierce battle in the country's tribal areas to root out the Pakistan Taliban.
Occasionally, drone strikes targeting a range of militants groups and their fighters also hit Pakistan Taliban fighters and commanders like Waliur Rehman, who was wanted by the U.S. for a spectacular attack planned inside Pakistan and carried out in 2009 against a CIA base in eastern Afghanistan. The suicide attack killed seven CIA workers.
The controversial drones program, meant to target militants in the tribal areas bordering Afghanistan, has also led to the deaths of civilians and become a lightening-rod issue. Many Pakistanis blame the spike in terrorism inside their country on drone strikes, arguing that the drone strikes radicalize ordinary Pakistanis.
Pakistani mountain tour operators familiar with Nanga Parbat expeditions told news organizations that escaping the scene of the crime could take more than a day and with only two or three possible escape routes – raising hopes that the up to 20 attackers involved could yet be caught.
Meanwhile, the debate over how to tackle the Pakistan Taliban raged online and on the airwaves.
"[Instead] of the focus being on how to prevent Pakistan from slipping further towards international isolation and internal instability, the question that will likely be asked most frequently, in the media, by the political class, by large chunks of civil society, is what can be done to stop drones strikes," read a Dawn newspaper editorial Monday morning.
"The problem with the drone debate is not that it is unimportant but that it tends to obscure a more fundamental and important question: what to do about the [Pakistan Taliban]?" continued the editorial.
For security analyst Imtiaz Gul, talking to the Pakistan Taliban would be a mistake.
"I don't think the [government] would be doing any service to the state of Pakistan by talking to a small band of criminals. Rather, it would be weakening the state," he said.
"Such a move would fill these groups with an unusual and bloated sense of victory over the state. So a state cannot be seen to be cowed down," he added.