New Delhi (CNN) Indian-controlled Kashmir was in lockdown Monday, with tens of thousands of new troops deployed into what is already one of the most militarized places in the world , as a number of prominent politicians were placed under house arrest and New Delhi announced contentious changes to the way the territory is administered.

A broad communications blackout left many people without access to the internet and phone services across the territory, with measures also in place to prevent public meetings.

The politicians under house arrest include at least two former chief ministers of the Indian state of Jammu and Kashmir, according to CNN affiliate CNN-News18

The state encompasses the section of the disputed territory controlled by New Delhi.

Kashmir is one of the world's most dangerous flashpoints . Claimed in its entirety by both India and Pakistan, it has been the epicenter for more than 70 years of an often violent territorial struggle between the nuclear-armed neighbors. A de facto border called the Line of Control divides it between New Delhi and Islamabad.

Tourists walk past Indian security forces in Jammu, India, on August 5, 2019.

Extra troops have been moving up to Indian-controlled Kashmir in recent days, while a major annual Hindu pilgrimage to a mountain shrine in the region was called off. Until last week, Indian authorities explained the move as a response to intelligence about a growing security threat in the region.

But on Monday, the government of Indian Prime Minister Narendra Modi said it was moving to revoke a provision known as Article 370 . In place since 1949, it gives Jammu and Kashmir the power to have its own constitution, flag and autonomy over all matters, save for certain policy areas such as a foreign affairs and defense.

The Modi government said it would introduce measures to modify Jammu and Kashmir's administrative status from a state to a union territory. In the Indian system, state governments retain significant authority over local matters. But New Delhi has more of a say in the affairs of a union territory.

The remote mountainous region of Ladakh, currently part of Jammu and Kashmir, will also be separated and turned into a standalone union territory, the government said.

Stranded Indian tourists walk to a railway station during restrictions in Jammu on August 5, 2019.

Modi's interior minister, Amit Shah, announced the measures in parliament, prompting an uproar from opposition parties.

"We stand by the constitution of India. We will give up our lives for the protection of the constitution of India. Today, the BJP (Prime Minister Modi's ruling Bharatiya Janata Party) has murdered the constitution and the democracy of the country," said Ghulam Nabi Azad, from the opposition Congress Party.

While anticipating opposition in the region, analysts said the security crackdown would -- for now -- restrict the ability of ordinary Kashmiris to react.

"They've put the state under a heavy security lock down and will shoot at sight anyone who tries to come out on the street," said Ajai Shukla, a New Delhi-based defense analyst and former military officer.

"It will be difficult for Kashmiris to come out with the conditions imposed, which I expect to continue for the immediate future."

Modifying administrative status 'illegal' says Pakistan

Pakistan's Foreign Secretary summoned India's High Commissioner on Monday to convey "a strong demarche on the announcements made and actions taken by the Government of India," it said in a statement.

"The Foreign Secretary called upon India to halt and reverse its unlawful and destabilizing actions, ensure full compliance with UN Security Council resolutions, and refrain from any further action that could entail serious implications," the statement added.

Pakistan's Ministry of Foreign Affairs "strongly" condemned India revoking Article 370 earlier, adding that Pakistan would "exercise all possible options to counter the illegal steps."

"The Indian Occupied Jammu & Kashmir is an internationally recognized disputed territory. No unilateral step by the Government of India can change this disputed status, as enshrined in the United Nations Security Council (UNSC) resolutions. Nor will this ever be acceptable to the people of Jammu & Kashmir and Pakistan," the Ministry of Foreign Affairs said in a press release.

Pakistan's Prime Minister Imran Khan also reached out to both Turkey's President Recep Tayyip Erdogan and Malaysian Prime Minister Mahathir Bin Mohamad on Monay to reiterate that the "illegal move by India would deteriorate the peace and security of the region," and further undermine relations.

Manoj Joshi, from the New Delhi-based Observer Research Foundation think tank, said the announcement would come as a "psychological shock" to Kashmiris.

"The so-called autonomy has eroded over the years," he said. "It was more of a symbolic thing but symbols are important, particularly in the context of Kashmiri politics and we may see more alienation.

Jammu and Kashmir is the only Muslim-majority state in Hindu-dominated India.

"It's a dramatic step with huge political risks. But on the other hand, the BJP as a party has never denied that it wants Article 370 to be abrogated."

Ahead of Monday's announcements, the mood in Kashmir was already tense, as residents rushed to secure essential supplies.

"There is panic all around and no one knows what is happening," Manzoor Ahmad, a local government employee in Srinagar, the main city in Indian-controlled Kashmir, told CNN.

"Kashmiri weather and politics you should never trust," Shaheena, a teacher in Srinagar, the main city in Indian-controlled Kashmir, told CNN.