“Though many mistakenly believe that sanctions are a relatively harmless way of forcing foreign countries to do what we say, we should be clear: sanctions are an act of war,” Paul wrote in an article published on Monday.
US Congress is set to vote for sanctions against Russia in the coming days.
Last week, the White House announced economic sanctions and blocking Russian officials' visas, but it has yet to impose them on specific Russian entities or officials.
American and European officials will meet in London on Tuesday to begin drawing up a list of which Russians might be affected by sanctions.
Ron Paul also said there is a “danger of an unimaginable conflict between the US and Russia.”
“We must demand a shift away from a war footing, away from incendiary rhetoric. We are broke and cannot afford to “buy” Ukraine. We certainly cannot afford another war, especially with Russia!” he said.
Paul explained that US debt officially stands at more than $17 trillion and the cost of the US invasion of Afghanistan and Iraq may be more than six trillion dollars.
“President Obama’s illegal invasion of Libya cost at least a billion dollars and left that country devastated. The costs of US regime change efforts in Syria are likely thus far enormous, both in dollars and lives. That’s still a secret,” he wrote.
“So who in his right mind would think it is a good time to start a war with Russia over Ukraine? And worse, who would commit the United States to bail out a Ukraine that will need at least $35 billion to survive the year?” the former lawmaker asked.
The Obama administration has beefed up its military presence in Europe, sending 12 F-16 fighter jets and 300 American troops in Poland in response to the crisis in Ukraine. Six F-15C Eagles and more than 60 American had also arrived at Siauliai air base, Lithuania.
Meanwhile, the USS Truxtun, a US Navy guided-missile destroyer, crossed Turkey's Bosphorus Strait and entered the Black Sea.
On Saturday, President Obama warned of possible “new measures” against Russia if Moscow fails to defuse the crisis.
The Pentagon has suspended its military ties with Russia, including joint maneuvers and port visits.
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