Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Russian military drills near neighboring Finland have provoked concern that northern Europe may be the next focus of Moscow's seemingly renewed appetite for redrawing its borders.

Troops and jet fighters from all four military regions of Russia were deployed Sunday about 150 miles east of the Finnish border, according to the English-language newspaper Finnbay. The Russian defense ministry said in a statement that the exercises were pre-planned and that more than 50 fighter pilots took part.

Finland was part of the Russian empire for 108 years, from 1809 until Russia’s withdrawal from World War I in 1917. The Karelia region, where the war games are taking place, straddles the Finnish border and has historically been a heavily militarized zone for Moscow.

But experts say that while Moscow appears to have seized another opportunity to flex its muscles, the threat of an armed invasion is very low.

"The people of Helsinki are nervous. What Putin is doing is sending shock waves through Europe"

According to Dr. Jonathan Eyal, international director at London's Royal United Services Institute think tank, there is "no question" that these exercises show that Russia is testing its power in the region, which was reshaped by the fall of the Soviet Union in 1991.

"In pure capability terms, the Russians are preparing an operation," Eyal said. "The question is: Is there an actual military threat? I do not think there will be."

Eyal said that while Russia's annexation of Crimea has put a spotlight on its foreign policy, tension with Finland and Sweden is not new. This was shown as recently as last year when Russian jets flew toward Swedish airspace, causing Stockholm to scramble its air force, he said.

But he said that Scandinavia and the Baltic states have sensed renewed danger in recent days because "Putin is an opportunist, and if the opportunity arises he will pick up on it."

Andrew Kutchins, a senior fellow at the Center for Strategic and International Studies, said the proximity of the drills had made the alarm most palpable in Finland.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

"The people of Helsinki are nervous," he said. "What Putin is doing is sending shock waves through Europe." However, Kutchins added that the likelihood of immediate military action appeared "very far-fetched."

Ukrainians living in Finland stage a demonstration in Helsinki on March 16 against Russia's actions in Crimea. Jarno Mela / Lehtikuva via AP, file

This anxiety was heightened Sunday after one of Putin's closest former advisers told the Swedish newspaper Svenska Dagbladet that the Kremlin would seek "historical justice" by reclaiming Finland and ex-Soviet countries as part of an enlarged Russian Federation.

"Putin's view is that he protects what belongs to him and his predecessors," wrote Andrei Illarionov, according to a translation by the Moscow Times.

"Parts of Georgia, Ukraine, Belarus, the Baltic states and Finland are states where Putin claims to have ownership," said Illarionov, who is now a senior fellow at the Washington, D.C.,-based Cato Institute.

Illarionov, who was chief economic adviser to Putin until 2005 and is described by the Moscow Times as an outspoken Kremlin critic, said Putin could argue the Communist revolution of 1917 was a "treason against national interests."

"It is not on Putin's agenda today or tomorrow," Illarionov added. "But if Putin is not stopped, the issue will be brought sooner or later."

"Finland isn't Ukraine"

The reason experts think Finland is more secure than Ukraine is that although neither are members of NATO, the former is more protected by its European Union membership.

"Finland isn't Ukraine," said Oliver Bullough, commentator and author of "Last Man In Russia." "It might not be a NATO member but it is in the European Union and you can bet that if Russia were to start invading members of the E.U., the E.U. would have something to say about it."

Bullough said the Russians had a "grudging respect" for the Finns because of the way they resisted Moscow's Red Army during World War II. Apart from Britain and the Soviet Union, Finland was the only European nation involved in the war to avert a foreign occupation.

Research consultant Kathleen McInnis pointed out that Finland is connected to NATO in that it has taken part in NATO-led actions, including Kosovo and Afghanistan.

"Recently there has been discussion in Finland about joining NATO, but opinion remains in favor of a defense partnership with Sweden," said McInnis, who is based at the London-based think tank Chatham House.

Add to that Finland's recent agreement to start discussions with Sweden over a defense partnership, and an incursion by Moscow looks less likely.

Perhaps the key difference between Finland and Ukraine is that Putin does not have a tangible excuse with which to exercise the Kremlin's influence abroad.

In the swift annexation of Crimea, he spoke of the need to protect ethnic Russians living in the peninsula from what he called the illegitimate fascist regime in Kiev.

But Eyal said that it is wrong to assume Russia's only option is a brute-force invasion.

"Russia could put pressure on Scandinavia not to come to the aid of the three Baltic states [Estonia, Latvia and Lithuania], which do have Russian ethnic minorities," he said. "Or they could warn in advance for Finland and Sweden not to join NATO. It's a key foreign policy for Russia to prevent NATO's enlargement."

Albina Kovalyova reported from Moscow. Alexander Smith and Alastair Jamieson reported from London.