As Russian troops march through the streets of Crimea and amass on Ukraine’s border with Russia, it’s still quiet here in Warsaw, where I am a visiting professor teaching about democratization and politics. Poles are watching the latest developments in their next-door neighbor with a mix of quiet anxiety and resignation. Poland, with a long and brutal history, is accustomed to restless neighbors and fluid borders. At the end of the 18th century and again 150 years later, Germans and Russians partitioned the country as they saw fit.

In the early 1980s, when a massive social movement rose up to challenge communism, its 10 million members faced martial law from Polish authorities who claimed Moscow forced their hands. During most of these crises, the Poles were largely left to their own devices with very little help from outside. Even after 25 years of aligning their country with Western institutions, such as NATO and the European Union, few here have any illusions that they are safe.

Local friends are renewing their passports. Some of them are filling out U.S. visa applications that only a couple of weeks ago seemed too long and burdensome to bother with. Some are withdrawing their money from banks in the fear that instability will spread and they will be left stuck in long ATM lines, as witnessed in Crimea. Their bags may not yet be packed, but euros pad their pillows.

Poles have good cause for alarm. For starters, Russian President Vladimir Putin has vowed to protect ethnic Russians in eastern Ukraine. Securing Kiev, the source of the problems in Ukraine, would be a logical and easy next step for him. Putin has also warned “meddlers” farther west, including Poland and Lithuania, that they are under watch. In his first televised comments after sending troops into Crimea two weeks ago, Putin singled out Warsaw and Vilnius for providing assistance to “fascists” in Kiev. “It's common knowledge they were trained in Lithuania, Poland and in Ukraine,” he said of the Maidan protesters opposing President Victor Yanukovich.

Poland’s neighbors to the north are no less secure. Both Estonia and Latvia have large Russian minorities that make up about one-fourth of their populations. Since the fall of the Soviet Union, ethnic Russians in both countries have often complained of being treated as second-class citizens. If there is any clear point at which Putin would logically stop his westward march, it is certainly not Crimea.