President Donald Trump was tight-lipped on his meeting with Russian President Vladimir Putin ahead of the G20 summit, saying it's 'none of your business.'

Speaking to reporters on the White House lawn on Wednesday before jetting off to Japan, Trump said of Putin: 'I'll have a very good conversation with him, what I say to him is none of your business.'

He is expected to meet Putin on the sidelines of the G20 in Osaka tomorrow, with discussions between world leaders throughout Friday and Saturday.

The president tore into China ahead of boarding Marine One and also said Iran's leadership was 'stupid' if they refused to 'do the right thing.'

President Donald Trump told a reporter his imminent talks with Putin were 'none of your business' as he free-wheeled on China and Iran before departing for Japan on Wednesday

Russian president Vladimir Putin attends a reception of honour in Moscow on Thursday - he is expected to meet Trump on the sidelines of the G20 on Friday

Trump continues to be plagued by accusations of mishandling relations with Moscow after saying he did not consider taking damaging information on opponents from foreign governments as interference.

When asked about the issue earlier this month, he told ABC News: 'It's not interference, they have information - I think I'd take it.'

He added: 'If I thought there was something wrong, I'd go maybe to the FBI.'

Trump descended Air Force One today with an umbrella over his head as he waved to the press having slammed a string a countries before his arrival in Japan.

Trump told reporters outside the White House yesterday that the U.S. had 'been ripped off by everybody over the years.'

'They're not ripping us off anymore,' the president added. 'A big difference right now. We're meeting with China. Just so you know, China has been paying us billions and billions of dollars. Until I got here they never paid this country ten cents, so we'll see what happens with China, with Russia, with Japan, with many countries.'

Trump is expected to meet with Chinese President Xi Jinping on Saturday, with a Beijing spokesman saying today: 'Chinese people don't believe in evil, are not afraid of pressure and have never bought tricks like this.'

Trump has already hit China with $200billion in levies and has appeared to threaten more.

President Donald Trump descends the stairs after arriving in Osaka on Thursday - he fired off a bullish tweet about India's 'unacceptable' tariffs while on board, as well as criticizing Germany, China, Vietnam and even the hosts Japan before his arrival

China's President Xi Jinping receives a bunch of flowers on his arrival at Kansai International Airport in Osaka on Thursday as he would have also received the news that Trump had rebuked the world's number-two economy

En route to Osaka Trump fired off a bullish tweet, chiding long-standing ally India for 'unacceptable' tariffs on American goods.

And before leaving he lambasted China for 'going down the tubes,' slammed Vietnam as the 'single worst abuser' on trade, lashed Germany as 'delinquent' on contributions to NATO, and said hosts Japan would not help the US in the event of WWIII.

Also on his agenda at the G20 will doubtless be the deepening crisis since his withdrawal from the Iran nuclear deal and the subsequent hostilities in the Gulf, including a US drone shot down last week and attacks on oil tankers.

Asked whether the ball was now in Iran's court following the president's remarks he wanted to 'make Iran great again,' Trump told reporters: 'The ball's in no court, you know what, Iran can do whatever they want, it's just fine I have plenty of time but they have a country that's in economic distress.

Iranian President Hassan Rouhani said the White House was 'mentally retarded' on Tuesday as Trump threatened 'obliteration'

The US maintain a drone shot down int the Gulf last week had not transgressed Iranian airspace as Tehran claimed

'It's an economic disaster right now. They could solve it quickly or they could solve it in ten years from now. Whatever they want is fine with me, whatever they want. I have all the time in the world. I'm sitting here, I've all the time in the world.

'In the meantime they have very strong sanctions, they have to live with those sanctions. But Iran should do the right thing for their people.

'The problem is I'm not sure that their leaders care for their people. If they do they'll make a deal. If they don't they're just thinking about themselves. And they're selfish and they're stupid if that's what they're doing.'

Iran maintains a US drone shot down in the Gulf last week had transgressed their airspace, as America denied their claims having already charged Tehran with attacking two oil tankers in the Strait of Hormuz earlier this month.

