President Barack Obama condemned Russia's intervention in Ukraine Wednesday as a "brazen assault" on the country's integrity and assured three former Soviet satellite states that NATO would defend them against any aggression by Moscow.
Obama said that Estonia, Lithuania and Latvia had lost their independence before to Moscow, but that "with NATO, you will never lose it again."
Speaking to a crowd of about 2,000 at the Nordea Concert Hall, Obama praised Estonia as a model NATO member and said, "There is no doubt the Baltics have made our alliance stronger."
Obama said that the Baltic states, which joined the alliance in 2004, share NATO's vision of a free and peaceful Europe, and that peace is now threatened by Russia's aggressions against Ukraine, calling it "a brazen assault upon a sovereign and independent nation."
The U.S. president urged NATO to send an "unmistakable message of support" to Ukraine and said the alliance would continue to help the country build democratic institutions, train its military and diversify its energy sources.
Baltic states' fears
Obama declared that NATO would be resolute in defending the three Baltic states on Russia's western border.
"We will defend our NATO allies, and that means every ally," he stressed. "In this alliance, there are no old members or new members, no junior partners or senior partners. They're just allies, pure and simple."
Obama also said the alliance must leave the door open to new members to counter what he called Russian aggression.
Earlier Wednesday, Obama announced plans to send more aircraft to the Baltics, as he seeks to reassure Estonia, Lithuania and Latvia, which are on edge about possible Russian threats.
The three nations fear that the separatist rebellion in eastern Ukraine could lead to problems within their countries. Similar to Ukraine, the three have sizeable Russian minorities and rely on Russian fuel deliveries.
In 1997, NATO agreed to not position its troops on Russia's border, but Obama said that declaration will be open to discussion at Thursday's NATO summit in Wales because "circumstances clearly have changed" with Moscow's involvement in Ukraine.
Air Force increase
Obama made his earlier remarks at a news conference Wednesday with Estonian President Toomas Hendrik Ilves in the Estonian capital, Tallinn, one day before the start of a key NATO summit in Wales.
Obama announced the U.S. would send more Air Force units and aircraft to the Baltics, and called Estonia's Amari Air Base an ideal location to base those forces.
Standing with Ilves, Obama ticked through a list of U.S. military resources already at work in the region, and said the U.S. has a duty under the NATO charter to the alliance's collective defense.
"It is unbreakable, it is unwavering, it is eternal. And Estonia will never stand alone," Obama said in Tallinn, Estonia's port capital.
The president also said all NATO members must do their fair share of defense spending in order to bolster the alliance.
Obama held up Estonia as an example of how all 28 NATO members must fulfill their pledges to contribute 2 percent of their gross domestic product to the alliance.
(Click here to see White House Fact Sheet on US / Estonia Partnership)
Baltic nations
Behind the closed doors at the Kadriorg Art Museum, Obama and Ilves later joined the leaders of the other Baltic states - Latvia and Lithuania - for broader security talks, where the crisis in Ukraine was again on the agenda.
The president has described the talks as a means of showing the three former Soviet republics "that we mean what we say with respect to our treaty obligations."
After their meeting, the four leaders delivered brief remarks. All four leaders spoke in English.
President Dalia Grybauskaite of Lithuania blasted Russian aggression, saying that it was not only an attack against Ukraine but also against peace.
She said her country appreciates U.S. and NATO commitments to the region and their commitment to Article 5.
Grybauskaite said, “Ukraine today is a front line for all of us, and we need to take this very seriously."
Latvian President Andris Berzins said he wanted to see U.S. troops and equipment in his country for “as long as necessary.”
Obama said his message to his counterparts was that the Baltic nations are among the United States’ most reliable allies in NATO. He said the United States’ commitment to their defense is “rock solid.”
“Here in the Baltics, the United States has stepped up its presence,” he said. The Baltics "will never stand alone."
NATO summit
On Thursday, Obama will join the leaders of the 27 other NATO nations for a two-day summit in Wales aimed at sharpening Western support for Ukraine, as Kyiv battles a months-long rebellion by pro-Russian separatists near the Russian border.
He said the summit is set to focus on proposals to establish a rapid-reaction NATO force capable of deploying quickly to eastern Europe.
Ukrainian President Petro Poroshenko is due to attend.
Earlier Wednesday, Ilves called for "a robust and a visible ally presence here in Estonia," arguing that such a presence would be the best way to deter any potential aggressors in the region — a clear reference to Russia.
Russia has voiced strenuous opposition to any NATO presence near its borders and Tuesday said it would review its military strategies if - as expected - NATO members endorse the creation of the force.
Before leaving Estonia late Wednesday, Obama met with U.S. and Estonian soldiers who had served together in Iraq and Afghanistan and are now training in Estonia, telling them their actions send a powerful message that as "NATO allies, we stand together."