The U.N. declared the Pakistani capital unsafe for the children of its international staff and ordered them out, putting the once tranquil city on par with Kabul and Somalia.
Underlining Pakistan's crumbling security situation, a suicide bomber failed in an attempt to assassinate a prominent anti-Taliban politician, and troops reportedly killed 27 militants in the restive northwest.
Pakistan is under intense U.S. pressure to combat militants responsible for rising attacks in neighboring Afghanistan. Its faltering efforts so far have been met with a blur of suicide attacks in Pakistani cities.
The U.N., which employs more than 2,000 people in Pakistan including about 100 foreigners, has not been hit.
However, the truck bombing of Islamabad's Marriott Hotel, which killed 54 people, including three Americans and the Czech ambassador, prompted the world body as well as foreign missions to review security.
Farhan Haq, a spokesman for the U.N. in New York, said the decision to relocate children was temporary.
"All essential staff will remain on duty, and all U.N. work will proceed as normal," Haq said. "The United Nations intends to return to regular staffing levels as soon as conditions allow."
Under the decision, U.N. expatriate staff will no longer be allowed to live with their children in the capital, the neighboring city of Rawalpindi or in Quetta, on the Afghan frontier.
Amena Kamaal, a U.N. spokeswoman in Islamabad, said only about 20 families were affected.
Much of the border region, including the city of Peshawar is already off-limits for U.N. families. Some of those affected can relocate to areas deemed safer, such as Lahore or Karachi.
But others are expected to leave Pakistan altogether, which could disrupt U.N. operations in the country as it faces severe economic difficulties and a crumbling of basic public services in militancy-torn areas.
Luc Chauvin, deputy representative in Pakistan for the U.N. children's agency, UNICEF, said seven of its 33 international staff would have to relocate or send children away.
He said UNICEF was buying laptops and installing Internet connections in staffers' homes to enable them to work without coming into the office — a potential target for attack.
"Of course there is a bit of an impact, but I think we can cope," Chauvin said of the extra precautions.
Khalif Bile, country representative for the World Health Organization, said the effect on its activities would be "insignificant." WHO works with the government on a campaign to eradicate polio that has been opposed by Islamic hard-liners.
Pakistan has suffered a surge in attacks by Taliban and al-Qaida-linked militants on government, military and Western targets over the last two years that has fanned fears about the nuclear-armed nation's stability.
Thursday's suicide bombing occurred as Asfandyar Wali Khan, the leader of a secular party that is part of the ruling coalition, was receiving guests to mark the end of the Islamic fasting month at his home in Charsadda.
Khan, whose party competes with Islamists for the loyalties of the region's ethnic Pashtuns, said the attacker was wearing a bulletproof vest as well as a suicide jacket and that police bullets failed to stop him.
"When he got close to me, my bodyguard overpowered him and threw him on the ground and that was when the blast happened," Wali told reporters afterward.
The guard and three others were killed. The politician was unscathed.
Charsadda lies near the tribal region of Bajur, where troops have been battling militants for more than two months. Police official Fazl Rabi said security forces killed at least 27 militants in various clashes near Bajur's main town of Khar Thursday. He gave no information on troop casualties.
Pakistani officials have blamed the Marriott blast on extremists holed up in tribal areas along the Afghan border. The same groups are suspected in suicide attacks that, according to army statistics, have killed nearly 1,200 people since July last year.
Several have taken place in the capital, including a car bombing claimed by al-Qaida that killed six outside the Danish Embassy in June. A blast killed a Turkish aid worker and injured 12 people, including four FBI agents, at a restaurant in March.
Pakistani authorities have sought to reassure an expatriate community for whom the leafy, grid-plan city at the foot of the Himalayas makes a comfortable home.
Extra checkpoints have sprung up across Islamabad, while paramilitary troops glower over the top of machine guns at the entrance to the diplomatic quarter, where many foreigners live and work.
However, the precautions have only made parts of the city resemble Kabul, which like trouble spots including Somalia and southern Nigeria, are non-family postings for U.N. international staff.
Baghdad and Khartoum are the only capitals where the U.N. is on a higher security level, Kamaal said.
Already on Wednesday, Britain announced about 60 children of its diplomats in Pakistan will return home and other countries may follow suit. Pakistan has long been a non-family posting for U.S. and Canadian diplomatic staff.