Julie Bishop says the consequences of Russia's invasion of Ukraine will be profound as the Russian president "rips up the rulebook".
"He is formidable. He is a risk taker. He has been threatening for many years that he won't tolerate an expansion of NATO membership on Russia's borders" Ms Bishop told the Seven Network.
"Now this is a full-scale invasion of Ukraine. Clearly, he is not bluffing (and) I cannot see a scenario where he will pull back."
Defence Minister Peter Dutton echoed the former deputy Liberal leader's comments, saying Mr Putin had retreated to a Cold War era mentality.
"(Mr Putin) believes that Ukraine's territory should be part of Russia and that's his intent. He's 69 years of age and he wants to see it in his lifetime," he told the Nine Network.
"We should be very careful about autocrats like this who have this world-view that they want to go back to a Cold War era or back to a period of conflict and that's a price that they're willing to pay."
But the defence minister says Russia will likely continue to focus on Ukraine, with any push into Poland invoking a response from the US-backed NATO security alliance.
"He knows that if he pushes into Poland, for example, there would be a reaction, rightly so from NATO," Mr Dutton said.
"It would be a shocking act and that's not something that's predicted at the moment."
The comments came as Ukraine's top diplomat in Australia called for more financial, military and humanitarian assistance for his country as Russia's invasion continued overnight.
An emotional Charge d'Affaires Volodomyr Shalkivskyi said Ukrainians remained shocked as residents desperately fight for their country or try to flee to the country's west.
"It's really painful to see the places where you spent your time usually with your family that's right now the place for the fighting," he told the Nine Network on Friday.
"It's our country and we need to defend it ourselves. But what we need is mounting pressure on Kremlin."
The United States unveiled another round of harsh sanctions and the United Kingdom has moved in lockstep.
Australia is expected to follow with further tranches of sanctions, with the prime minister flagging moves on over 300 members of the Russian parliament.
Mr Dutton said the US and its allies had done all they could to deter Russian President Vladimir Putin.
"What more can the world do? There can be forces sent in and then you would be saying, Why have we entered into a nuclear war?" he said.
"We've offered, with the rest of the world, very strong sanctions against Putin. We've been united in our call against Russia to not undertake this action and now we're seeing the tragic circumstances unfold."
Mr Dutton also urged the world to remain focused on the human suffering in the region.
"We need to concentrate on the human tragedy that's unfolding in Ukraine," he said.
"We need to prevent it as best we can, but we need to make sure that we continue to report it because that's the human cost and that's the pressure that needs to come to bear on President Putin."
The defence minister again called on Chinese President Xi Jinping to put pressure on the Kremlin.
"China and Russia have entered into this frankly unholy alliance and President Xi has a lot of power he can exert over President Putin," he said.
"He has chosen not to do that."