VILNIUS, Lithuania — A large plaque located in a central square in Lithuania’s capital city enshrines a phrase uttered by U.S. President George W. Bush during a visit in 2002: “Anyone who would choose Lithuania as an enemy has also made an enemy of the United States of America.”

It’s a muscular promise; together with the subsequent accession to both NATO and the European Union in 2004, it fueled Lithuania’s giddy millennial boom.

As a correspondent for the Financial Times in the early 2000s, I witnessed firsthand the country’s rapid transformation from post-Soviet backwater to a confident European nation that wasn’t afraid to stick a finger to the Russian bear. I remember joyous free concerts in the capital’s squares and the universal sense of euphoria that greeted the country’s entry into NATO. For many Lithuanians, membership in the transatlantic alliance heralded the “end of history” as they had known it.

Fast-forward a little more than a decade. Today’s dark mood of fear and insecurity couldn’t be more different. The arrival of an international NATO battalion of 450 troops under German leadership, along with Leopard 2 tanks and armored vehicles in Lithuania this month (other troops will also be stationed in Poland and the other Baltic States) hasn’t done much to calm frayed nerves.

[Lithuania] has reintroduced mandatory military service, refurbished Soviet-era bomb shelters, and even distributed pamphlets with detailed instructions for dealing with an armed invasion.

Many Lithuanians are fearful U.S. President Donald Trump’s ambivalence toward NATO could result in an attack by an emboldened Russia, and so they are making contingency plans for “worst-case” scenarios.

Friends in bars described how they packed an extra suitcase and filled large containers of gasoline in case they had to flee the country at the last minute. Some even bought boats to escape via the Baltic Sea, as many did when the Red Army came through during World War II.

When one British expat boasted of buddying up with a Lithuanian oligarch who owns a private jet, his Lithuanian wife chided him, asking whether the “airport would be open when Russian tanks roll through the country.”

For citizens of a prosperous European nation and an integral part of the transatlantic alliance, the statements struck me as extraordinary — and surreal. Lithuania is not Ukraine after all; and even in Ukraine’s capital Kiev, where I’ve been based for the past few years, these kinds of conversations would be beyond the pale.

“People are definitely more edgy these days, after the incidents in Georgia and Ukraine,” said Nerijus Maliukevicius, a professor of political science at Vilnius University. “And Trump’s comments calling NATO ‘obsolete,’ and his kind words toward Putin, have added to Lithuanians’ fears about the future.”

Lithuania has been one of Ukraine’s strongest supporters in Europe, one of the only countries to provide “lethal” weapons to the country’s military. Its fiercely anti-Russian President Dalia Grybauskaitė has visited Kiev as often as America’s former Vice President Joe Biden, and is close to Ukrainain President Petro Poroshenko.

It’s exactly this unabashed support for Ukraine that has put the country in the Kremlin’s crosshairs. Russian jets repeatedly violated Lithuanian airspace last year, and senior advisers to the president have had their accounts hacked. The country has also been spooked by Russia’s transfer of nuclear-capable Iskander missiles to its enclave of Kaliningrad, which shares a long border with Lithuania. And then there’s Trump, who has repeatedly called NATO into question and praised Lithuania’s arch enemy, Russian President Vladimir Putin.

The fear of a Russian invasion might seem overblown, given Lithuania’s NATO membership and the fact that it has much fewer Russian-speaking citizens (just 6 percent of its population) than neighboring Estonia and Latvia. But the government doesn’t feel the Russian threat is to be taken lightly.

It has reintroduced mandatory military service, refurbished Soviet-era bomb shelters, and even distributed pamphlets with detailed instructions for dealing with an armed invasion. The handbook advises the population to look out for foreign spies and to turn collaborators over to the government.

Meanwhile, voluntary paramilitary groups, like the Riflemen’s Union, have seen a sharp spike in membership since Russia’s actions in the Ukraine. It now boasts more than 10,000 members, including the mayor of Vilnius. The government, meanwhile, plans to relax firearm restrictions this year, under a new law that allows gun ownership for “defense of the country.”

“We’re not scaremongering, we’re just being vigilant,” explained Lithuanian Foreign Minister Linas Linkevičius during an interview with POLITICO in Vilnius. “After Russia’s aggression in Ukraine, we realized that we’re much more vulnerable than before.”

Though Linkevičius is concerned by Trump’s comments about NATO, he claims to understand his motivation. “He’s a businessman, and he looks at the bottom line. We understand that there are no free lunches anymore,” he admitted, with a quick laugh.

Trump has repeatedly criticized countries that don’t contribute their fair share toward NATO’s budget, and Lithuania has moved quickly to increase its defense spending to 2 percent of its GDP, as called for by the treaty, so the U.S. President does not see it as a “free-loader.” The government hopes to go one step further and increase its military spending to 2.5 percent of its GDP within the next two years.

Linkevičius hopes these steps — and its continuing contribution to NATO troops in Afghanistan, where two of its soldiers have died since 2001 — will ensure support for the country under the new administration. He was also heartened by the appointment of Russia hawk and NATO supporter James Mattis as Trump’s secretary of defense. And, echoing Trump, he noted the country is moving ahead with plans to build a six-foot high, razor-wired fence on its border with the Russian enclave of Kaliningrad.

“We need strong leadership and deterrence in these difficult times,” he said.

However, not all Lithuanians support the government’s strident anti-Russian stance.

“Lithuania is like the little guy in the bar that picks a fight with the bully because he knows that the bouncers have his back,” said a local friend. “We’re provoking Russia and alienating our Russian minority with this fear-mongering and also backing ourselves into a corner.”

If NATO indeed begins to unravel during a Trump presidency, his words could prove to be prophetic.

Vijai Maheshwari is a writer and entrepreneur based in Kiev, Ukraine. He spent six years in Moscow in the 1990s, and was also editor in chief of Russian Playboy.