Thousands of Pakistani protesters demanding the release of jailed former Prime Minister Imran Khan have forced their way through security barriers and defied a lockdown to enter the capital, Islamabad.

The demonstrators from Khan’s Pakistan Tehreek-e-Insaf (PTI) party, many wielding slingshots and sticks, clashed with security forces on Tuesday as they tried to reach a central square – D-Chowk – in the face of tear gas and rubber bullets. By early afternoon, many had reached the square.

The government has invoked Article 245 of the constitution, which allows a civilian government to call in the army to help it implement “law and order” domestically.

What is happening in Pakistan?

Convoys of protesters started making their way to Islamabad on Sunday from different parts of the country, led by various PTI leaders.

The main convoy from Peshawar in the restive northwestern province of Khyber Pakhtunkhwa, a party stronghold, was led by Khan’s wife Bushra Bibi alongside Chief Minister Ali Amin Gandapur.

On Monday, Bibi told Khan’s supporters that the protests would continue until he was freed.

Before the demonstration, police detained more than 4,000 protesters across the country, and the government suspended mobile and internet services.

Why is Imran Khan in jail?

Khan, 72, was first arrested on May 9, 2023, in a corruption case. The Supreme Court ordered his release two days later, but he was arrested again in August 2023 and sentenced in a case related to the illegal sale of state gifts. He has been in detention ever since.

The former prime minister, who was removed from power in April 2022 after losing a no-confidence vote in parliament, has more than 150 cases against him, which the PTI claims are politically motivated.

What are the protesters’ demands?

Apart from Khan’s release, the PTI is also calling for the following:

Revoke controversial constitutional amendments: The 26th amendment was rushed through and passed by both houses of parliament, the Senate and the National Assembly, this October. The changes radically alter the judiciary, setting a fixed term of three years for the Supreme Court’s chief justice, who will now be selected by a parliamentary committee. It also weakened the powers of the top court, with, for example, constitutional cases and those involving fundamental rights to be transferred to “constitutional benches” instead. PTI’s Omar Ayub Khan, the leader of the opposition in the National Assembly, said the amendments are “suffocating a free judiciary”.

Return ‘stolen mandate’: After the February 8 general election, marred by allegations of vote rigging and delayed results, a six-party alliance, including the Pakistan Muslim League-Nawaz (PMLN) and Pakistan People’s Party (PPP), formed a government with Shehbaz Sharif as prime minister. PTI members allege that the governing coalition comprises “mandate thieves”. On November 17, Haleem Adil Sheikh, the PTI president in Pakistan’s Sindh province, said the party will reclaim the “stolen mandate”.

Free political prisoners: Khan’s initial arrest on May 9 sparked nationwide protests. Dozens of demonstrators were arrested and some are still behind bars.

Call to all Pakistanis!

This 24th November let’s come together for Captain’s #FinalCall for Haqeeqi Azaadi.

Our key demands:

-Revoke the 26th Amendment and restore the Constitution.

-Return the stolen mandate.

-Free all political prisoners.

Time to stand united… pic.twitter.com/IP2oH7fSAh

— PTI (@PTIofficial) November 22, 2024

What is the latest?

Khan’s supporters clashed with police, who used tear gas and rubber bullets on protesters, on Monday night and Tuesday.

“These supporters are determined. They’re passionate. They have been removing obstacles, which has taken them several days just to reach Islamabad,” said Al Jazeera’s Kamal Hyder, reporting from Islamabad.

At least four paramilitary rangers and two policemen have been killed and dozens injured in clashes with PTI members since Monday, the Ministry of Interior said.

Islamabad was placed under security lockdown on Monday and Tuesday, with gatherings of any kind banned and educational institutions closed. Schools were also shuttered in neighbouring Rawalpindi.

Amid this chaos in the capital, Belarusian President Aleksandr Lukashenko arrived in Pakistan on Monday for a three-day visit. He was received by Sharif at an airbase in Rawalpindi.

Sharif said in a statement, “These disruptive elements do not seek revolution but bloodshed.”

Al Jazeera’s Hyder described Islamabad as a city “under virtual siege”.

“So far, we have not seen the military actively involved in trying to stop the protesters, but paramilitary forces and thousands of police forces have been mobilised,” he said.

Where are the protesters now?

On Tuesday, some protesters reached D-Chowk, near important government buildings, including the prime minister’s office, where they want to hold the sit-in.

Also called Democracy Chowk, it is a popular protest venue. It is located in what is called the Red Zone.

They earlier managed to cross the G-9 highway, roughly 15km (9.3 miles) from D-Chowk, despite the path being blocked with barriers such as large shipping containers and barbed wire. Security forces were also using stun grenades alongside tear gas to disperse the crowds.

What did Mohsin Naqvi say?

Naqvi, the federal interior minister, said the government had suggested Sangjani, on the outskirts of Islamabad, as an alternative venue for the protest during late-night talks with the representatives of protesters.

He also said PTI leaders, including Gohar Ali Khan, met Khan in his prison cell twice on Monday night for advice on this, but they have not reported that they received a response.

Naqvi warned the protesters against crossing the Red Zone and marching to D-Chowk, saying the government would ensure “extreme measures” and arrests.

What is Article 245?

Article 245 of the constitution allows the civilian government to call in the army to aid it in enforcing “law and order”.

The first clause of the article says: “The Armed Forces shall, under the directions of the Federal Government defend Pakistan against external aggression or threat of war, and, subject to law, act in aid of civil power when called upon to do so.”

It adds that the validity of directions made by the federal government under the first clause cannot be questioned.

The article also bars any high court from giving a verdict regarding an area where the military has been deployed.

Is internet connection disrupted?

Internet disruptions have been reported in multiple cities in Pakistan since late last week. On Saturday, internet watchdog NetBlocks posted an update saying WhatsApp backends have been restricted in the country, making the sharing of media such as photographs or voice messages difficult.