SIAULIAI AIR BASE, Lithuania (Reuters) - NATO should permanently deploy anti-aircraft weapons in the Baltics to deter Russia, Lithuania’s president said on Thursday as the United States put Patriot missiles on display after including them in an exercise in the region for the first time.

The permanent deployment of the advanced air defense system would be the next step in NATO’s new deterrent in the Baltics and Poland, which includes ground troops on rotation. Moscow says it is an unjustified military build-up on its borders.

“It would be really meaningful to have such weapons in the Baltic region. It would ensure a greater security for all our countries,” Lithuania’s president Dalia Grybauskaite told reporters on Thursday, standing in front of Patriot missiles deployed as part of a two-week NATO exercise.

“We would gladly host them,” she said of the missiles. “We are always ready”.

Since Russia annexed Crimea peninsula from Ukraine in 2014 and began providing weapons and troops to separatist rebels in eastern Ukraine, NATO has stepped up its deployments in the Baltics, eastern Poland and around the Black Sea.

Lithuania, Latvia and Estonia, which were once ruled from Moscow but are now part of NATO and the European Union, are set to triple their defense spending by 2018, compared to 2014, in order to deal with any threats from Russia.

But with small militaries and limited budgets, the Baltics are reliant on help from allies for advanced capabilities, including long-range anti-aircraft weapons.

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Earlier this month, the United States approved the possible sale of seven Patriot missile defense systems worth $3.9 billion to Romania.

Poland said it signed memorandum with the United States to purchase Patriot missiles, having indicated earlier in the year it expects to buy eight for $7.6 billion [nL8N1JX0TG].

Describing air defenses as “the weakest link” in NATO’s eastern flank, Grybauskaite called on the alliance to tackle the issue by a NATO leaders’ summit in Brussels in July 2018.

However, she also left open the possibility of stationing the missile batteries out of the Baltics, as long as they were focused on protecting the region.

“As the Patriots have a very long range, it does not really matter where they are deployed, whether that is in the Baltics or in Poland, or somewhere else. What is important is the speed of response to any air threat,” she said.

The U.S. battery did not fire a shot in Lithuania during the exercises, which also involved troops from Britain, Poland and Latvia, a U.S. commander said.

But Baltic officials said the deployment demonstrates the willingness of United States to bring such advanced weaponry to the region, despite Moscow’s protests.

Russia says the North Atlantic Treaty Organisation is increasing the risk of conflict in Europe, citing the alliance’s biggest modernization since the Cold War and a greater NATO troop presence in eastern Europe.