WISCONSIN: Republican presidential front-runner Donald Trump on Tuesday said that amongst all the presidential hopefuls only he can solve the problem of "radical Islamic terrorism".

During an interview with CNN anchor Anderson Cooper, Trump termed Pakistan "a vital problem" for the United States (US) "because they have a thing called nuclear weapons", adding, "They have to get a better hold of the situation."

Related: 'I alone can solve', Trump says after Lahore terror

Trump had tweeted 'I alone can solve' after a suicide blast in Lahore on Sunday which killed at least 74 people. Explaining his earlier statement, he said: "When I see they [the attackers] put it [the bomb] in a park and there were mostly Christians although many others were killed...I think it is absolutely a horrible story," said Trump. "But I am talking about radical Islamic terrorism. I will solve it better than anyone else running," he claimed.

The Lahore attack was condemned by other politicians and celebrities around the world, many of whom took to social media to express sorrow and anger over the tragedy.

'Japan, S. Korea should have nuclear weapons'

When questioned about nuclear security and American defence policy, the billionaire said that although the US has traditionally provided military support to Saudi Arabia, Japan, Germany and South Korea, it may be time to change the existing policy.

Trump was of the opinion that support of these countries had resulted in a budget deficit for the US, so they should start protecting themselves.

"Saudi Arabia makes $1 billion a day. We support them militarily and they pay us a fraction of what they should be paying us, of the cost," he said, adding that the US is "better off" if they stop spending money on the defence of other countries.

"They [supported countries] should protect themselves or they should pay us," he said.

"Our military expenditure isn't just on ourselves. We're protecting all these nations all over the world. We can't afford to do it anymore."

"We are better off if Japan protects itself against this maniac in North Korea," he said, referring to North Korean leader Kim Jong Un.

"Wouldn't you rather let Japan have nuclear weapons when North Korea is having them? We don't want to pull the trigger... Nobody is afraid of our president," he said.

Related: N. Korea may force Japan to go nuclear: Nightmare for China, Russia

Although it has been "in US policy for decades to prevent Japan getting nuclear weapons", according to Anderson Cooper, Trump said, "Maybe it's going to have to be time to change."

When questioned about the implications of such a suggestion, Trump said nuclear proliferation "is going to happen anyway, it's just a matter of time".

Alternatively, he suggested, it may be time to "get rid of them entirely".

"The only global warming I'm worried about is nuclear global warming."