Prime Minister Narendra Modi on Monday said INS Arihant, India’s first nuclear ballistic missile submarine, has completed its first deterrence patrol. Modi received the submarine’s crew on Monday.

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

Modi said the submarine has enhanced the country’s security needs. “It is a major achievement for our entire nation,” the prime minister said. “True to its name, INS Arihant will protect the 130 crore Indians from external threats and contribute to the atmosphere of peace in the region.”

Modi termed it a historic day because it “marks the completing of the successful establishment of the nuclear triad”. He said the nuclear triad – which has the ability to launch nuclear weapons from air, land and water – would be an “important pillar of global peace and stability”.

The Arihant is India’s first indigenously built naval submarine. It was commissioned by Modi in August 2016 after being declared operation-ready six months earlier.

The submarine can carry nuclear-tipped ballistic missiles, The Hindu had reported in 2016. Strategic strike nuclear submarines are capable of lurking undetected in deep sea levels for months, can carry nuclear weapons and provide India with second strike capability – the ability to strike back after a nuclear attack from another nation.