BELGRADE, Serbia (AP) -- For some European countries watching Russia's brutal war in Ukraine, there are fears that they could be next.
Western officials say the most vulnerable could be those who aren't members of NATO or the European Union, and thus alone and unprotected -- including Ukraine's neighbor Moldova and Russia's neighbor Georgia, both of them formerly part of the Soviet Union -- along with the Balkan states of Bosnia and Kosovo.
But analysts warn that even NATO members could be at risk, such as Estonia, Latvia and Lithuania on Russia's doorstep, as well as Montenegro, either from Moscow's direct military intervention or attempts at political destabilization.
Russian President Vladimir Putin "has said right from the start that this is not only about Ukraine,'' said Michal Baranowski, director of the German Marshall Fund's Warsaw office.
"He told us what he wants to do when he was listing his demands, which included the change of the government in Kyiv, but he was also talking about the eastern flank of NATO and the rest of Eastern Europe," Baranowski told The Associated Press in an interview.
As Ukraine puts up stiff resistance to the two-week-old Russian attack, Baranowski said "it's now not really clear how he'll carry out his other goals."
But the Biden administration is acutely aware of deep concerns in Eastern and Central Europe that the war in Ukraine may be just a prelude to broader attacks on former Warsaw Pact members in trying to restore Moscow's regional dominance.
EU foreign policy chief Josep Borrell has said that "Russia is not going to stop in Ukraine."
"We are concerned for neighbors Moldova, Georgia, and the Western Balkans," he said. "We have to keep an eye on Western Balks, particularly Bosnia, which could face destabilization by Russia."
A look at the regional situation:
Like its neighbor Ukraine, the ex-Soviet republic of Moldova has a separatist insurgency in its east in the disputed territory known as Trans-Dniester, where 1,500 Russian troops are stationed. Although Moldova is neutral militarily and has no plans to join NATO, it formally applied for EU membership when the Russian invasion began in a quick bid to bolster its ties with the West.
The country of 2.6 million people is one of the poorest countries in Europe, and it's hosting tens of thousands of Ukrainians who fled the war. The invasion has prompted heightened concerns in Moldova not only over the humanitarian crisis, but also because of fears that Putin might try to link the separatists east of the Dniester River with Ukraine via the latter's strategic port of Odesa.
U.S. Secretary of State Antony Blinken visited Moldova last week and pledged: "We stand with Moldova and any other country that may be threatened in the same way."
Moldovan President Maia Sandu said there was no indication yet the Russian forces in Trans-Dniester had changed their posture, but stressed that the concern was there.
"In this region now there is no possibility for us to feel safe," Sandu said.
War erupted between Russia and Georgia in August 2008 when Georgian government troops tried unsuccessfully to regain control over the Moscow-backed breakaway province of South Ossetia. Russia routed the Georgian military in five days of fighting and hundreds were killed. Afterward, Russia recognized South Ossetia and another separatist region, Abkhazia, as independent states and bolstered its military presence there.
The government of West-leaning Georgia condemned Russia's invasion of Ukraine, but hasn't shown the same solidarity that Kyiv displayed during the Georgia-Russia war. Hundreds of Georgian volunteers were stopped by authorities from joining an international brigade fighting Russia in Ukraine.
Georgia's seemingly neutral stance has turned out thousands in nightly rallies in central Tbilisi in solidarity with Ukraine. Last week, Georgia's government applied for EU membership just days after declaring it wouldn't accelerate its application as fears of a Russian invasion grew.
Memories of Soviet rule are still fresh in Latvia, Lithuania and Estonia. Since the invasion of Ukraine, NATO has moved quickly to boost its troop presence in its eastern flank allies, while Washington has pledged additional support.
To residents of the Baltic nations -- particularly those old enough to have lived under Soviet control -- the tensions prior to the Feb. 24 invasion recalled the mass deportations and oppression. The three countries were annexed by Josef Stalin during World War II and only regained their independence with the breakup of the Soviet Union in 1991.
They joined NATO in 2004, putting themselves under the military protection of the U.S. and its Western allies. They say it is imperative that NATO show resolve not just in words but with boots on the ground.
"Russia always measures the military might but also the will of countries to fight," said Janis Garisons, state secretary at Latvia's Defense Ministry. "Once they see a weakness, they will exploit that weakness."
Blinken, who visited Latvian capital Riga on Monday, said the Baltics have "formed a democratic wall that now stands against the tide of autocracy" that Russia is pushing in Europe.
It would be hard for Russian troops to reach the Balkans without engaging NATO forces stationed in all the neighboring countries. But Moscow could destabilize the region, as it already does, with the help of Serbia, its ally which it has been arming with tanks, sophisticated air defense systems and warplanes.
The Kremlin has always considered the region its sphere of influence although it was never part of the Soviet bloc. A devastating civil war in the 1990s left at least 120,000 dead and millions homeless. Serbia, the largest state in the Western Balkans, is generally blamed for starting the war by trying to prevent the breakup of Serb-led Yugoslavia with brutal force -- a move resembling Moscow's current effort to pull Ukraine back into its orbit by military force.
There are fears in the West that the pro-Moscow Serbian leadership, which has refused to join international sanctions against Russia, could try to use the attention focused on Ukraine to further destabilize its neighbors, particularly Bosnia, where minority Serbs have been threatening to split their territories from the joint federation to join Serbia. Serbian officials have repeatedly denied they are meddling in the neighboring states, but have given tacit support to the secessionist moves of the Bosnian Serbs and their leader, Milorad Dodik.
The Russian Embassy in Bosnian capital Sarajevo warned last year that should Bosnia take steps towards joining NATO, "our country will have to react to this hostile act." Joining NATO will force Bosnia to take a side in the "military-political confrontation," it said.
EU peacekeepers in Bosnia have announced the deployment of about 500 additional troops to the country, citing "the deterioration of the security internationally (which) has the potential to spread instability."
Kosovo, which split from Serbia 1999 after a NATO air war against Serbian troops, has asked the U.S. to establish a permanent military base in the country and speed up its integration into NATO after Russia's invasion of Ukraine.
"Accelerating Kosovo's membership in NATO and having a permanent base of American forces is an immediate need to guarantee peace, security and stability in the Western Balkans," Kosovo Defense Minister Armend Mehaj said on Facebook.
Serbia said the move is unacceptable.
Kosovo's 2008 declaration of independence is recognized by more than 100 countries, mainly Western nations, but not by Russia or Serbia.
Montenegro, a former ally that turned its back on Russia to join NATO in 2017, has imposed sanctions on Moscow over the war in Ukraine and is seen as next in line in the Western Balkans to join the EU. The country is divided between those favoring pro-Western policies and the pro-Serbian and pro-Russian camps, raising tensions.
Russia has repeatedly warned Montenegro's pro-Western President Milo Djukanovic, who led the small Adriatic state into NATO, that the move was illegitimate and without the consent of all Montenegrins.
Russia may hope to eventually improve its ties with Montenegro in a bid to strengthen its presence in the Mediterranean.