ISLAMABAD -- Tens of thousands of opposition supporters, led by a former cricket star, Imran Khan, and a cleric, Muhammad Tahir-ul Qadri, converged on the Pakistani capital late Friday for what they billed as an extended protest movement to oust Prime Minister Nawaz Sharif.
The two cavalcades, which were loosely allied but operated separately, arrived in Islamabad in the pouring rain, at the end of a slow and occasionally violent journey across Punjab province.
Khan's supporters clashed with pro-government activists as they passed through the city of Gujranwala. People on each side threw stones and accused one another of starting the trouble.
The protests are the most potent threat yet to Sharif's 14-month-old government, which also has been dogged by tensions with the military high command. Khan hopes that, by taking a large crowd into central Islamabad, he can force Sharif, whom he accuses of vote-rigging, to resign and hold new elections.
But the crowds that followed Khan into the capital Friday fell far short of predictions of a "million man march," and bad weather further dampened the atmosphere. Khan's senior lieutenants warned the government against employing tactics of intimidation against them.
"You are playing with fire," said Jahangir Tareen, a senior leader, during a news conference Friday afternoon, addressing Sharif. "We are peaceful, but it is not our weakness."
Mass street movements are an integral part of democratic politics in Pakistan, often used by opposition politicians to press their demands. But Khan's crusade has been met with sharp criticism in the news media in recent weeks from Pakistanis who say his demands are exaggerated, especially at a time of pressing security challenges.
Those challenges were underlined Thursday when militants attacked two military air bases in the western city of Quetta, setting off battles in which 10 militants were killed and several security officers were wounded, officials said Friday.
The violence in Baluchistan offered fresh evidence of the country's ongoing security threat. A faction of the Pakistani Taliban claimed responsibility for the attacks.
"We have carried out the attacks to avenge the killing of innocent civilians during the ongoing military operation in North Waziristan," Ehsanullah Ehsan, a spokesman for the faction, said by telephone, referring to a military operation in the tribal belt that started in June.
Earlier, a spokesman for an apparently different Taliban faction also claimed responsibility for the attack.
Ehsan claimed the Taliban had killed 35 security personnel and destroyed two airplanes. But a military spokesman said the attackers had failed to penetrate the perimeter of the bases and that both were "fully functional and open" Friday.
It was the third such attack on an air facility in Pakistan since May.
Military officials said militants, firing guns and throwing grenades, first attacked the Samungli air base on the edge of Quetta's main civilian airport. They were met with heavy return fire from base guards and were unable to break through the external perimeter, the officials said. Three attackers were captured, they said.
An hour later, a second group of attackers struck the Khalid army aviation base, which is on the far side of Quetta. All of the attackers, described as suicide bombers, were killed in a gunbattle that lasted several hours.
The attacks took place during Pakistan's annual Independence Day celebrations. Hours earlier, Sharif and the army chief, Gen. Raheel Sharif, who is not related to the prime minister, visited Baluchistan province to inaugurate a historic building that was burned by Baluch separatists last year.
A Section on 08/16/2014