Australia will commit an initial payment of more than $4 million to Ukraine for military assistance, Prime Minister Scott Morrison has confirmed.
The $US3 million payment will go to NATO's Trust Fund for Ukraine to support non-lethal military equipment and medical supplies.
Mr Frydenberg says the full details of the support package - including lethal military aid - will be revealed on Monday after being finalised with his counterparts in the United States and United Kingdom.
"It is not going to be the same sort of quantum that the United States or the United Kingdom would provide, but where we can act is in joining the international efforts to put in place sanctions," he told ABC Radio National on Monday.
Australian-targeted financial sanctions and travel bans on Russian President Vladimir Putin and members of Russia's Security Council came into effect at midnight on Sunday.
The treasurer says the sanctions the Australian government put in place last week have already had an effect on Russia's economy.
But he says it is "no secret" Putin has ambitions beyond invading Ukraine.
"Vladimir Putin starts with Ukraine, but who's next? That is the question," he said.
"This is the first major interstate conflict within Europe since the Nazis were defeated. This is a direct challenge to the international rules-based order that has underpinned prosperity in Europe for more than 70 years."
Deputy Prime Minister Barnaby Joyce says any threats made by Russia to use nuclear weapons should be taken seriously.
"We hope that he is just using provocative language and he has no intention of backing it up," Mr Joyce told Channel 7 on Monday.
"The smartest thing for Mr Putin to do is to stop."
Meanwhile, Mr Frydenberg has warned Australians not to travel to Ukraine to take part in military action.
"Do not go into the conflict zone," he said.
"Under Australian law, Australian citizens cannot go and fight in conflict zones unless they're fighting with a foreign government and a foreign army, but we have very clear travel advice ... please do not travel into a conflict zone."
