— The morning of the attack, Subhe Abu Khalifa did not get up for work, telling his mother he was too tired and his feet hurt. He had spent the night watching and rewatching footage of a Palestinian woman, who the Israeli police say stabbed a Jewish man in the back in Jerusalem’s Old City, being harassed and shot.
Instead of going to his job as an apprentice electrician, Mr. Khalifa, 19, sharpened a knife he bought the day before, according to an account friends later gave his brother, then plunged it into an Israeli near Police Headquarters. With that, he joined a cadre of young Palestinians who, spurred on by social media, have independently decided to attack Israelis, killing seven and wounding scores in two dozen episodes since Oct. 1, authorities said.
The violence escalated again on Tuesday, with two deadly outbreaks in Jerusalem, one where the police said two Palestinians tried to commandeer a public bus with a gun.
Three Israelis were killed along with at least two of three Palestinian attackers. Palestinian officials said 30 of their people had been slain this month, mostly after stabbings or in roiling clashes across East Jerusalem and the West Bank, as well as at the border fence separating Israel from the Gaza Strip.
“What we see now is like an octopus with many hands but no brain,” said Orit Perlov, an expert on Arab social media at the Institute for National Security Studies in Tel Aviv. “You don’t need something sophisticated. We’re talking about 15-year-old boys. You just write the word ‘it’an,’ stab in Arabic, and then whoever has a knife in his house and wants to go, that’s it.”
The current violent uprising has a very different character than the second Palestinian intifada, whose suicide bombings were orchestrated by well-organized armed groups. It consists of spontaneous outbursts by individual young people unaffiliated with any formal political movement. Their weapons are mainly small knives, but also screwdrivers and even a potato peeler. And their inspiration seems to come from their ubiquitous smartphones, which provide an endless stream of videos like the one Mr. Khalifa viewed over and over before he struck.
These leaderless assailants live in communities that applaud those who have died, often without any mention of their own violent deeds. They are motivated by social media campaigns — some by Hamas and other militant Islamist movements, many by enraged individuals — replete with glistening blades and how-to guides. Further fanning the flames are viral videos — also broadcast by official Palestinian networks — of Israelis fatally shooting attackers, whose names are immediately added to the Facebook scroll of so-called martyrs.
The clarion call is the defense of Al Aqsa, the mosque at the heart of a contested Old City compound that Palestinian leaders continue to insist Israel wants to divide, despite the prime minister’s insistence otherwise.
Israel has struggled to try to quell the attacks through ever-stricter tactics, only to find that its crackdown has fueled a Sisyphean cycle: When troops stormed the Shuafat camp after Mr. Khalifa’s attack, for example, they faced an unruly mob of men, some of them armed, and killed one of his neighbors.
Two days later another Shuafat man stabbed two Israeli police officers and was also shot dead. Another riot exploded in the camp.
“There’s a viral nature to these attacks: One person goes out, they get killed, then they get glorified, it makes other people want to go out,” said Daniel Nisman, president of the Levantine Group, an Israeli security analysis firm. “You have a significant number of people who are willing to basically commit suicide attacks; they just don’t have access to sophisticated weapons.”
Fourteen of 23 alleged assailants since Oct. 3 were 20 or younger, and one was just 13, according to a Levantine Group compilation of police reports. At least 16 of the 23, like Mr. Khalifa, are from East Jerusalem, where the Palestinian Authority has no presence and residents complain of severe neglect by Israeli institutions.
One crude cartoon making the rounds on Facebook, including on the official Palestinian TV page before it disappeared late Tuesday, depicts an Israeli soldier as an ape, accompanied by a pig, over a bloodied youth. Another has a close-up of a menacing blade, and is captioned: “This is not difficult. To the closest kitchen, and go in the name of God.”
An Israeli security official said that except for the alleged perpetrators of Tuesday’s Jerusalem attacks, and five Hamas members arrested in connection with the fatal shooting of an Israeli couple in front of their four children on Oct. 1, none of the recent suspects were affiliated with any known group or had ever been previously arrested.
Most were not religious, the official said on the condition of anonymity under his agency’s rules, noting that none of the men wore beards, as is common for devout Muslims.
They decided to act “the morning of the stabbing” or “maximum a day or two before,” he added, giving security forces “zero chance to prevent it.”
Ms. Perlov, the Arab social media expert, said Israeli and Palestinian security services had arrested hundreds of online instigators in recent months, but that it had done little good because “ideas are becoming immortal — you can take down pages but it will multiply itself.”
In retrospect, Muhanad Halabi’s relatives said they should have seen something coming.
Mr. Halabi, a 19-year-old law student at Al Quds University, had been morose since the Sept. 22 death of his friend Dia Talahma, 21, who the Israeli military said died when a grenade he was throwing at troops in the occupied West Bank detonated too early. Mr. Halabi replaced his profile picture with one of Mr. Talahma.
His mother, Suheir Halabi, said that on Oct. 2, her son “wasn’t normal,” explaining, “He always says good night, but the night before he made sure to come and kiss me, he kissed my hand and he asked me, ‘Do you love me, Mom?’”
The next morning, Mr. Halabi kissed his brother, Mostafa, 10, asking if he was upset about anything, then stopped to visit his ailing grandmother before heading to the university. On campus, he spoke at a rally.
“He said we need to stand with our sisters who are being attacked at the Aqsa, we need to defend it,” a cousin, Mahmoud, said people there told him. “He was telling the people I’m promising you something.”
A few hours later, Mr. Halabi fatally stabbed two Orthodox men in the Old City and wounded one of their wives and 2-year-old son before being shot dead. On Facebook, he is now admired as “the lion,” or “the thunder” that unleashed the new uprising.
Mustafa al-Khateeb, in contrast, “never posted anything that had to do with Al Aqsa or anything political,” according to his aunt, Bakriya al-Khateeb Bakri, 41, who was also his Facebook friend. Mr. al-Khateeb, 18, a senior at the private Ibrahimi School, recently changed his profile picture to show him next to a shiny Mercedes-Benz.
He was shot dead on Monday by Israeli police officers after trying to stab one of them, according to the Israeli authorities, who said the officer was unharmed because he wore a protective vest. But Ms. Bakri insisted that “they shot Mustafa for no reason whatsoever, like they have been doing to every other Palestinian lately.”
Saeb Erekat, the chief Palestinian negotiator, said at a news conference on Tuesday that Israel was carrying out “extrajudicial executions” and listed the names and ages of each slain Palestinian. Among them was Ishaq Badran, 16, who was sprayed with seven bullets, witnesses said, after he stabbed a man in the face Saturday on a cobblestone curve of cafe tables outside the Old City.
Several Palestinians said they encouraged Ishaq to flee after the stabbing, but he seemed desperate to die dramatically.
“I tried to hold him so he wouldn’t do anything else,” said a man who works at a juice stand and spoke on the condition of anonymity for fear of reprisals. “I told him go, go, and he doesn’t want to. He was just holding the knife in his hand. He said, ‘I want to be a martyr.’”
The next evening, scores of men and boys mourned at Ishaq’s home, wearing freshly made pendants and Palestine scarves with his picture. His father, Qasem Badran, said Ishaq, too, was agitated by the video of the female stabber shot earlier in the Old City.
“He came to his mother and he was crying, he opened his cellphone and showed the video,” said Mr. Badran, 40. “He said, ‘Look, Mom, what they’re doing to the Muslim girls and no one is standing up for them.’ ”
The woman in the video is Shorouq Dweiyat, 18, who is a first-year student at Bethlehem University, where relatives said she started a campaign last Tuesday encouraging students to donate 10 shekels, or about $2.50, to families of the “martyrs.” On Wednesday, they said, she was running late for class and decided to go instead for breakfast in the Old City and pray at Al Aqsa.
The Israeli police said that Ms. Dweiyat stabbed a Jewish man in the upper back, near his head, and that he pulled out his personal pistol and shot her. “She tried to escape and within seconds policemen were able to pounce on her,” a commander, Avraham Peled, said at the scene. “We stopped her, searched her, identified she was hurt and saw that she put a knife down next to her. We found another knife in her bag.”
The knives cannot be seen in the video that Palestinians like Mr. Khalifa, the electrician from the Shuafat camp, kept showing one another. The videos have been removed from social networks, but many Palestinians said Israelis were seen yanking at Ms. Dweiyat’s veil and long coat before the alleged attack.
Mohammed Abu Khalifa, 28, said that after seeing the video, his brother posted on Facebook about Al Aqsa, “telling people to wake up, our sisters are having their clothes ripped off.”
The next morning, before sharpening his knife and hunting for an Israeli, Mohammed added, Subhe “put on Facebook that he’s planning on following the footsteps of all the martyrs.”
He did not fulfill that wish, instead getting arrested without injury. He smiled broadly for the smartphone cameras, an image that was also celebrated on social networks.