Russia has suspended all transport and postal links with Georgia in an escalation of the bitter dispute between the two nations sparked by the arrest of four Russian military officers last week.
Russian officials say the sanctions are in response to what President Vladimir Putin has called "the actions of a bandit state", and will be in effect until further notice.
Russia imposed the measures despite Georgia's release of the four men it accused of spying.
Russian Defense Minister Sergei Ivanov was on hand to greet the four officers when they arrived in Moscow late Monday night.
The sanctions have left passengers in train and airport terminals stranded, unable to travel in either direction.
Some passengers in both countries spent the night in the airport when their flights were abruptly canceled at midnight when the measures took effect.
Other measures may soon include a ban on all money transfers between the two countries, something that is sure to have a strong impact on Georgia's fragile economy.
Economists estimate that about 20 percent of the Caucasus Mountain nation's gross domestic product comes from Georgians working in Russia and sending money home to relatives.
The Georgian economy is already feeling the impact of an earlier Russian ban on the import of all Georgian wines and mineral water, its primary exports.
Russian Parliament Speaker Boris Gryzlov sought to clarify the reasons for the sanctions.
He says the measures are aimed at the regime of Georgian President Mikhail Saakashvili, and despite the deep respect he has for the Georgian people they must choose whether they are on the right path with him as their leader.
President Putin and other top Russian officials have made no secret of their intense anger at the pro-Western policies of Georgia's young, U.S.-educated Saakashvili.
But the arrest of the four officers has become a major development in the increasingly bitter dispute with its southern neighbor.
Kremlin officials were especially livid when Georgia aired video footage it says show the four men engaged in espionage.
The European Union says the Russian sanctions against Georgia are disproportionate, and urged the two countries to calm down and try to settle their differences.
But President Putin says Mr. Saakashvili is acting at the behest of what he calls his "foreign sponsors", an apparent reference to Western nations.
The Kremlin has long been angered by Mr. Saakashvili's desire to have Georgia one day enter the NATO military alliance, while the Georgian leader criticizes Russia for supporting two separatist regions in Georgian territory.