Wary of their powerful neighbour Russia, the Baltic states of Lithuania and Latvia plan to double defence spending while Estonia will maintain its strong level after watching Moscow take over Crimea.

The three countries of 6.3 million people will mark on Saturday a decade since joining the NATO military alliance, a move seen as a bulwark against unwanted Russian overtures.

Relations between the Baltic states and Russia have been tense since they broke free from the crumbling Soviet Union more than two decades ago.

But security fears have risen in the ex-Soviet states since Russian forces intervened in Crimea, leading to a disputed referendum and the annexation of the Russian-speaking Ukrainian peninsula.

Estonia and Latvia are also jittery that their large ethnic-Russian minorities, which make up a quarter of the population in both countries, could make them vulnerable to interference from Moscow.

"Russia's aggression against Ukraine brought some politicians back to the reality that it is important to finance defence," Lithuanian Defence Minister Juozas Olekas told AFP on Friday.

Lithuania and Latvia say they will increase defence spending by 2020 to NATO's recommended two percent of gross domestic product, from the current level of one percent of GDP.

They had slashed military spending as part of austerity measures designed to pull their economies back from the brink of collapse during the global financial crisis.

Estonia already meets NATO's two percent benchmark and "does not plan to increase or decrease spending", defence ministry spokesman Peeter Kuimet told AFP.

"As we see what is happening in Ukraine, we realise once again just how fragile freedom is," Lithuanian President Dalia Grybauskaite told parliament this week as parties across the political spectrum vowed to spend more on the military.

"Until help arrives, we must be able to defend ourselves."

The moves to boost spending come after US President Barack Obama said Wednesday he had "some concern about a diminished level of defence spending" among NATO members.

"The situation in Ukraine reminds us that our freedom isn't free," Obama said in Brussels. "We have to be willing to pay" for mutual security to ensure the maintenance of a "deterrent" force.

- No illusions -

But none of the Baltic states has any illusions that they could defend themselves without NATO help in the face of any imminent Russian threat.

"It's important to counterbalance current developments with adequate NATO deterrence measures by strengthening the NATO and allied presence in the Baltic region," Latvian Defence Minister Raimonds Vejonis told AFP on Friday.

"Rapid security developments in Ukraine indicate the importance to react immediately on short notice."

Since Moscow's entry into Crimea, both NATO and Washington have been at pains to emphasise their commitment to mutual defence under Article 5 of the North Atlantic Treaty.

Visiting Vilnius last week, US Vice President Joe Biden said Washington was mulling whether to send forces to the Baltic states.

He also stressed the United States' "ironclad" commitment to mutual defence under NATO.

The US has already sent six extra F-15 fighter jets to boost NATO's long-standing air patrols over the Baltic states along the Russian border.

Britain, Denmark and France also offered additional warplanes.

NATO has deployed AWACS reconnaissance aircraft to overfly Poland and Romania as part of its efforts to monitor the crisis in Ukraine.

The regional tension in the Baltics has moreover spawned a spike in interest in military service unseen in the last decade.

"The number of military service requests increased by 20 percent in March compared to the same period last year," said Captain Skomantas Povilionis, spokesman for Lithuania's defence chief.

Germany ready to give military aid to Baltic states over Ukraine crisis: report
Francfort (AFP) March 29, 2014 - Germany is ready to provide military assistance to the three Baltic nations, all former Soviet republics, as part of NATO efforts to counter fears over Moscow's swift absorption of Crimea, German weekly Der Spiegel reported Saturday.

The defence ministry in Berlin could send "up to six air force planes for air policing operations to the Baltic" region, the news magazine said in its online edition.

Germany also stands ready to provide a navy vessel.

A decision will be announced during a NATO meeting in Brussels on the Ukraine crisis on Tuesday, Der Spiegel added.

A foreign ministry official contacted by AFP said Germany would "take part, if necessary, in stepped-up routine operations within the alliance perimeter".

Estonia, Latvia and Lithuania have been rattled by Moscow's territorial ambitions in Ukraine after the ouster of the country's pro-Russian president Viktor Yanukovych last month.

The three Baltic states which joined NATO in 2004 on Saturday marked the 10th anniversary of their membership.

In Vilnius two US fighter jets roared across sunny skies as Lithuanian President Dalia Grybauskaite hailed NATO membership as "vitally important" to Baltic security.

The three countries of 6.3 million people were under Moscow's thumb before the collapse of the Soviet Union in 1991.

US Vice President Joe Biden said earlier this month Washington could dispatch forces to the region to reassure the ex-Soviet NATO allies which are nervous about Russia's takeover of Crimea.

Washington has already sent six extra F-15 fighter jets to step up NATO's air patrols over the Baltics, and Britain, Denmark and France have also offered aircraft.