WASHINGTON : Commenting on the submarine launch of cruise missile Babar-III by Pakistan, the state department said  that the US continue to urge all states with nuclear weapons to exercise restraint regarding nuclear and missile capability testing and use.

Answering a question by an Indian journalist in his briefing, John Kirby, state department spokesman said they encourage efforts to promote confidence building and stability with respect to those capabilities.

Pakistan test fired the Cruise missile Babur-III on Monday from a submarine and successfully hit its ground target at least 450 kilometres (km) at distance.

The test of the submarine launched missile has given the country with a credible second nuclear strike capability.

Babur 3 was stated to be a sub-launched variant of the land-based Babur 2, which was tested in December 2016 and features improved avionics and accuracy. Babur 3 features “underwater controlled propulsion and advanced guidance and navigation features, duly augmented by Global Navigation, Terrain and Scene Matching Systems.”

A second-strike capability was a “manifestation of the strategy of measured response to nuclear strategies and postures being adopted by India.”

Development of Babur 3 was also hailed as “a step towards [Pakistan] reinforcing policy of credible minimum deterrence.”

Mansoor Ahmed, a postdoctoral research fellow at Harvard University's Belfer Center for Science and International Affairs and an expert on Pakistan’s nuclear program and delivery systems, said Babur 3 is a “significant milestone” in Pakistan’s effort to complete its nuclear triad.

“It has proven the speculation that Pakistan will not follow India’s pathway to a naval leg of the triad via nuclear submarines but opt for a more cost-effective solution tailored to its own strategic calculus and capabilities,” he said.

Combined with the very low frequency communication facility unveiled last year, Ahmed believes Pakistan’s Naval Strategic Force Command can now deploy nuclear-armed cruise missiles on its conventional submarines to ensure a credible second-strike capability.