Polish riot police and coils of razor wire faced off Tuesday with migrants, including families with young children, who were camped just across the border in Belarus, amid a tense standoff on the European Union’s eastern border.

Polish authorities reported that the situation on the border was calm overnight and early Tuesday, but authorities said they were bracing for any possibility of unrest. Poland’s Defense Ministry said Tuesday that a large group of Belarusian forces was moving toward the migrant camp.

There was no way to independently verify what was happening, however. Journalists have limited ability to operate in Belarus, and a state of emergency in Poland has kept reporters and others out of the border area.

A day earlier, tensions flared as a large group of migrants sought to illegally push their way into Poland, according to video footage posted on social media by Polish authorities.

Polish forces repelled them, and the migrants settled into a camp overnight, with tents and campfires along the border, in near-freezing temperatures.

Monday’s siege escalated a crisis along the border that has been simmering for months, in which the authoritarian regime of Belarusian President Alexander Lukashenko has encouraged migrants to illegally enter the EU.

The EU reacted Tuesday by tightening visa rules for Belarus officials over what it is calling a “hybrid attack” against the 27-country bloc.

EU headquarters said it was “partially suspending” an agreement with Belarus that eases visa rules.

The move hits Belarusian members of the government, lawmakers, diplomats and top court representatives. It requires travelers to provide extra documents and pay more for visas.

In videos posted on Twitter, tents and campfires can be seen as the Polish police play an announcement warning the migrants that entering Poland is allowed only at official border crossings, where visas are required.

But as of early Tuesday, the nearest crossing point, in Kuznica, in the northeast of the country, was closed.

The situation marks an escalation in months of migration pressure on Lithuania, Poland and, to a lesser extent, Latvia, the three EU states on the bloc’s eastern border with Belarus. The EU says Belarus is building the pressure, intending to destabilize the bloc in retaliation for Western sanctions.

Polish Prime Minister Mateusz Morawiecki, accompanied by Defense Minister Mariusz Blaszczak, went to the border Tuesday morning to meet with border guards and other security officials. Morawiecki praised them, also on behalf of the EU, for their “effective defense of our border.”

“We do not know what else Lukashenko’s regime will come up with — this is the reality,” Morawiecki said.

Meanwhile, the Lithuanian government Tuesday asked Parliament to declare a state of emergency along the border with Belarus for a month, starting at midnight.

The state of emergency would be in place along the border in a three-mile-wide strip, as well as in migrant accommodation facilities in Vilnius, the capital, and elsewhere in the country.

The measure would include restricting the right of irregular migrants accommodated in Lithuania to communicate in writing or by phone except to contact the country’s authorities.

The migrants are mostly people from the Mideast and Africa who have seized on the opening of a new migration route to enter Europe, often seeking to reach family members who have already immigrated to Germany or other countries in Western Europe.

Poland has received strong signals of support and solidarity from the EU, fellow EU countries and the United States as it deals with its border crisis.

Germany’s outgoing interior minister, Horst Seehofer, said Tuesday that all EU countries “must stand together, because Lukashenko is using people’s fates with the support of Russian President Vladimir Putin to destabilize the West.” He called for the European Commission to support Poland in securing the border.

“The Poles are fulfilling a very important service for the whole of Europe,” he said.

So far, Poland’s ruling nationalists have refused help from Frontex, the EU’s border agency.

Many of the migrants fly to Minsk, the capital of Belarus, on tourist visas, and from there travel by taxi to the border with Poland. The EU is seeking to pressure airlines not to facilitate the travel.

Although direct flights from Iraq to Minsk were suspended in August, migrants have been flying into Belarus via commercial and chartered flights from Syria, Turkey, the United Arab Emirates and even Russia, according to recent internal EU migration reports seen by the Associated Press.

On social media, smugglers have advertised transportation from Belarus to Germany by car. Drivers smuggling people across the Polish-German border were mainly from non-EU countries, according to the reports, although there were also EU nationals involved.

Many of the migrants have ended up in Germany. But some continued their journey all the way to Finland by ferry via Sweden, one report said.