Pakistan most dangerous country in the world, says former US defence secretary

Former US Defence Secretary Jim Mattis on Tuesday described Pakistan as the most dangerous country in the world, warning of that the rising threat of radicalisation in the nuclear-armed country.

Pakistan, a country of 200 million with a sizeable nuclear arsenal, has been plagued by militant groups and a radicalised society could spell problems in the future, he said.

"Of all the countries I've dealt with, I consider Pakistan to be the most dangerous, because of the radicalisation of its society and the availability of nuclear weapons," he wrote in his book, "Call Sign Chaos: Learning to Lead".

"This is a much worse problem, I think, than anyone is writing about today."

He also said Pakistan doesn't "have leaders who care about their future".

"We could manage our problems with Pakistan, but our divisions were too deep, and trust too shallow, to resolve them."

Pakistan has been at war with neighbour India several times since independence in 1947. 

Tensions persist over the contested region of Kashmir, which is split between Pakistan and India control, both nuclear powers.

Pakistan Prime Minister Imran Khan has sought to ease tensions, but the Indian Hindu Nationalist government's decision to end semi-autonomy for a region of Kashmir it controls led to a new crisis.

India accuses Pakistan of providing a haven to militant groups, some of which have carried out bloody attacks on civilians.

Mattis - a former military man - served as defence secretary under President Donald Trump from January 2017 until January this year.

He reportedly quit his role as defence chief due to Trump's plans to withdraw troops from Syria, shortly after the defeat of the Islamic State group.