Malcolm Turnbull is taking Russian President Vladimir Putin's advice not to trust anybody.
Mr Putin met United States President Donald Trump in Finland on Monday, and the US leader revealed he trusted his Russian counterpart ahead of his own intelligence services.
"President Putin himself said you shouldn't trust anybody," the prime minister told 3AW radio in Melbourne on Tuesday.
"I certainly don't trust President Putin when he said he wasn't responsible for the shooting down of MH17, which was four years ago today."
Four years after 38 Australians died when Malaysia Airlines flight MH17 was shot out of the sky, Australia is still looking for answers.

The reconstructed front of MH17, which was shot down over Ukraine. Source: AAP
Foreign Minister Julie Bishop said today's fourth anniversary of the 2014 disaster was a time to keep pushing.
"We remain resolute in pursuing accountability and seeking justice for the victims and their loved ones," she said.
Ms Bishop has met in the past week with the Australian Federal Police for a briefing on the investigation into the downing of MH17.
"Over 450 AFP have been involved since the tragedy," she said.
"This includes in the search and recovery phase of the operation in July 2014, as well as in an investigative role."
Next week Ms Bishop will visit the United Kingdom to speak to new Foreign Secretary Jeremy Hunt, and she plans to raise the issue with him.

Foreign Affairs minister Julie Bishop. Source: AAP
"Australia values the UK's strong support, including in the UN Security Council, in calling on Russia to answer for its actions in relation to the tragedy," she said.
"Holding Russia responsible for its role in the downing of MH17 is vital."
Australia and the Netherlands have requested negotiations with Russia over the circumstances behind the attack on the plane.
The flight was on its way from Amsterdam to Kuala Lumpur when pro-Russian rebels fighting Ukrainians brought it down near Donetsk on July 17, 2014.
The attack killed 298 people, including 38 Australians.
Meanwhile, foreign ministers from G7 nations have called on Russia "to account for its role" in the aircraft's downing.

President Donald J. Trump (L) and Russian President Vladimir Putin (R) shake hands during a joint press conference Source: REX/Shutterstock
Mr Turnbull's comments about trust come after US President Trump said his intelligence agencies told him Russia had interfered in the 2016 US election, but he said Mr Putin rejected it in their meeting.
"I will say this, I don't see any reason why it would be (Russia). President Putin was extremely strong and powerful in his denial today," Mr Trump said.
When Mr Turnbull was asked if he believed Russia had meddled in the US election, he replied:
"I find the evidence that's been produced by the American intelligence community to be very compelling."
"But obviously there is a difference of opinion inside America."