Russia is reviewing whether or not it was legal for the Soviet Union to recognize the independence of the Baltic states nearly 25 years ago.

A source "familiar with the situation" said Tuesday the Russian Prosecutor General's office is checking the legality of the Soviet Union's 1991 decision to cede back the states of Lithuania, Latvia and Estonia, according to a report by Interfax.

Two parliamentary deputies, members of the United Russia party loyal to President Vladimir Putin, launched the investigation.

Russia's review outraged her Baltic neighbors, who are already fearful of the growing threat of a highly militarized Russia after it sent troops into the Ukraine and annexed Crimea.

The investigation is an "absurd provocation," said Lithuania's foreign minister Linas Linkevicius, while Estonian Foreign Minister Keit Pentus-Rosimannus called it "legally absurd."

"The entire issue is legally absurd," said Pentus-Rosimannus to Reuters. "It serves as yet another example of the resurgent imperialistic mood that unfortunately exists in Russia."

The Kremlin sought to distance itself from the plans Wednesday.

"We are required by law to consider all requests we receive, regardless of their content. Some of them lack common sense," spokeswoman for the prosecutor-general's office, Marina Gridneva, told Russian news agencies. "In this case, it is clear the matter has no legal prospects."

"In the Kremlin we were not familiar with this initiative," said Kremlin spokesman Dmitry Peskov. "And I struggle to understand the essence of this initiative."

Russia was opposed to Lithuania, Estonia and Latvia joining NATO in 2004, and an overwhelming number of Russians (83 percent) currently oppose the Ukraine joining NATO. In March, Russia responded to NATO troops brought in to quell tensions by putting the Russian Northern Fleet on full combat alert.

Lithuania was established 11 months before the collapse of the Soviet Union, when the Soviet army stormed a TV station headquarters in Vilnius in January 1991. After news of Russia's decision to review Lithuania's legality, Lithuanian President Dalia Grybauskaite issued a strong statement:

"Our independence was gained through the blood and sacrifice of the Lithuanian people. No one has the right to threaten it."