Prime Minister Narendra Modi on Monday congratulated the crew of INS Arihant, the indigenously-built nuclear-powered ballistic missile submarine, on the completion of its first deterrence patrol.

“India’s pride, nuclear submarine INS Arihant successfully completed its first deterrence patrol!” the PM tweeted.

“I congratulate all those involved, especially the crew of INS Arihant for this accomplishment, which will always be remembered in our history,” he wrote.

Receiving the crew of the submarine in New Delhi, the PM said that the success of the submarine is “a big step towards strengthening national security”.

“For the country’s enemies, it is an open challenge. It is a fitting response to those indulging in nuclear blackmail; credible nuclear deterrence is the need of the hour,” he said.

Calling the success of INS Arihant “a major achievement for our entire nation”, the PM said that the submarine will protect Indians from external threats and contribute to the atmosphere of peace in the region.

He also pointed out that the success of INS Arihant marks the completion of the successful establishment of the nuclear triad.

“India’s nuclear triad will be an important pillar of global peace and stability. India is a land of peace. Values of togetherness are enshrined in our culture,” he said underscoring that peace is India’s strength and not weakness.

“Our nuclear programme must be seen with regard to India’s efforts to further world peace and stability,” he said.

President Ram Nath Kovind, too, congratulated the Indian Navy and Indian defence manufacturers on the submarine’s success.

“Congratulations to the Indian Navy and to our defence technologists on the completion of INS Arihant’s first deterrence patrol. The successful mission of this indigenous nuclear sub is a landmark moment in our nation’s security preparedness,” the President wrote on Twitter.

Congratulations to the Indian Navy and to our defence technologists on the completion of INS Arihant’s first deterrence patrol. The successful mission of this indigenous nuclear sub is a landmark moment in our nation’s security preparedness #PresidentKovind

— President of India (@rashtrapatibhvn) November 5, 2018

Defence Minister Nirmala Sitharaman and Home Minister Rajnath Singh were among those who tweeted to congratulate the Indian Navy and the country on the successful patrol of the INS Arihant.

“India has achieved completion of her nuclear triad with the first successful deterrence patrol by INS Arihant. This places India in the league of the few countries that can design, construct and operate Strategic Strike Nuclear Submarines (SSBN),” wrote Sitharaman.

India has achieved completion of her nuclear triad with the first successful deterrence patrol by INS Arihant. This places India in the league of the few countries that can design, construct and operate Strategic Strike Nuclear Submarines (SSBN).

— Nirmala Sitharaman (@nsitharaman) November 5, 2018

Congratulating the sailors, Singh said that it is “a momentous occasion for India and will go a long way in safeguarding our strategic and security interests”.

Congratulations to brave Indian sailors on INS Arihant for successfully completing its first deterrence patrol marking the successful realisation of the nuclear triad. This is a momentous occasion for India and will go a long way in safeguarding our strategic & security interests

— राजनाथ सिंह (@rajnathsingh) November 5, 2018

INS Arihant, the lead ship of the Arihant-class submarines, is India’s first indigenously built naval ship. Launched in 2009 by former Prime Minister Manmohan Singh, the ship was commissioned by PM Modi in August 2016, six months after it was declared operations ready.

The 111-metre-long ship can carry nuclear tipped ballistic missiles. Being a nuclear submarine, INS Arihant can remain underwater for months undetected. India has two nuclear-powered submarines, the other being the Russian-made INS Chakra.

A deterrence patrol essentially involves a submarine patrolling the seas with the ultimate weapon for a second-strike capability after its nation comes under nuclear attack from an enemy country.