Brzezinski believes the next step of sanctions imposed by the U.S. and its allies will be the continuation of "pin-prick sanctions" against specified individuals and a limited set of economic entities in Russia.
On Friday, President Barack Obama said the U.S. is prepared to impose targeted sanctions against Russia. However, the president is apparently having a difficult time garnering European support for stronger sanctions, according to Reuters.
Read More US, allies to impose targeted sanctions on Russia
For sanctions to have an effect, Brzezinski said they need to be financial ones "that would hit the Russian economy hard and resonate deeply through the corridors of the Kremiln."
However, those tougher sanctions could mean trouble for Western energy companies doing business in Russia.
At the moment, he said, names such as Exxon-Mobile and Shell aren't affected by the current sanctions because they are important sources of investment and are helping develop Russia's industrial base. However, he warned if the sanctions really have an influence on the Russian economy, the companies should be prepared for the Russian government to take action against them.
Read More Some Western firms could face Russian retaliation
—By CNBC's Michelle Fox
—Reuters contributed to this report