The European Union is once again scrambling to respond to a crisis on its external borders, what officials have called a "hybrid attack" orchestrated by the Belarusian regime to push migrants toward the bloc's external border.

After the situation escalated dramatically on Monday, European Commission President Ursula von der Leyen said: "The Belarusian authorities must understand that pressuring the European Union in this way through a cynical instrumentalization of migrants will not help them succeed in their purposes."

But what can the EU really do?

EU response 'slow and irresolute'

Until now, EU member states have opted for a "gradual approach," trying to pile pressure on Belarusian President Alexander Lukashenko and the regime in Minsk without wreaking havoc on the lives of ordinary Belarusians. So far that's included four rounds of sanctions targeting 166 people and 15 entities linked to the regime.

But with the situation escalating in the wrong direction, critics argue the EU's method has proved ineffective.

"The European Union's response has been slow and irresolute," Judy Dempsey, a senior fellow at the  Carnegie Europe think tank, told DW. "Lukashenko, likely with the support of [Russian President] Vladimir Putin, has used the migration issue to punish Brussels for slapping sanctions on his regime. Both Moscow and Minsk know that Europe's visceral reaction to migration is one of its greatest vulnerabilities."

But the EU has insisted its approach is working.

"Why do we have reason to believe the sanctions are biting?" European Commission spokesperson Peter Stano told reporters on Tuesday. "Because the Lukashenko regime starts to behave like a gangster regime, because it's hurting them and they don't know what else to do."

Brussels has accused Belarus of trying to destabilize the EU by bringing in migrants and encouraging them to cross its borders — especially Poland and Lithuania — in retaliation for EU sanctions.

EU teeing up broader sanctions

Now, more sanctions appear to be on the way. Von der Leyen is calling on EU member states to "finally approve" an extended sanctions regime, which is now making its way through the bloc's internal procedures.

Technical work to broaden the scope of new sanctions to include human trafficking is ongoing, an EU diplomat who asked not to be named told DW. The move would beef up the EU's power to target those facilitating the migration routes it claims Belarus is using to shuttle people toward the bloc.

The new sanctions package may also include measures against Belarusian airline Belavia and companies leasing aircraft to the firm, the diplomat said.

EU ambassadors are likely to give their initial backing to the new sanctions criteria on Wednesday, according to several other diplomats, with further technical work to follow. If this is completed in time, foreign ministers would then be expected to give their political green light next Monday.

Beyond a fifth package of sanctions, the EU is also mulling new measures against airlines it believes are "active in human trafficking" — in other words, involved in transporting migrants to Belarus.

According to one Polish diplomat, the number of flights into Belarus each week has increased by more than 50 since the start of the border crisis.

The European Commission is regularly monitoring the patterns, frequency and occupancy of flights to Minsk from around a dozen countries including Iran, Syria, Qatar, India, South Africa and Russia, spokesperson Stano confirmed to DW.

Working with countries of origin, transit

The EU will also be flexing its diplomatic muscles in the coming days, sending its foreign affairs and migration chiefs to those countries which are sites of origin and transit for Minsk-bound migrants.

Brussels hopes these meetings will "ensure that [countries] act to prevent their own nationals from falling into the trap set by the Belarusian authorities," a spokesperson said.

EU officials will be pushing foreign governments to better coordinate on the return and repatriation of their citizens, and to consider suspending flights to Minsk.

But overall, Dempsey's expectations for swift and effective measures are not high. "Don't expect any quick decisions," said the Carnegie Europe expert.

Poland turns down EU support

Beyond these efforts, Brussels is legally limited in what it can achieve. Over the past few weeks, frustration has been mounting in Brussels over Poland's refusal to ask for support in managing the border crisis.

While neighboring Lithuania has drafted in help from the EU's border agency Frontex, the bloc's police agency Europol and the European Asylum Support Office, Poland has not requested EU support.

"Poland has an ongoing battle with Brussels over the rule of law situation, and so Poland is trying to show that it can manage the problem alone. Asking the EU for help would not necessarily be an easy thing for the Polish government to do," Joanna Hosa of the European Council on Foreign Relations told DW.

Warsaw and Brussels have been involved in a drawn-out standoff over judicial independence and the primacy of EU law. In late October, the European Court of Justice imposed a fine of €1 million ($1.2 million) a day on Poland to prevent what it called "serious and irreparable harm'' to the EU's legal order and values.

"If the situation escalates as quickly as has been happening recently, it's possible that Poland realizes it must request help," Hosa said. "The EU would have to convince Poland that this won't be linked to the rule-of-law fight. If Poland is to cooperate with the EU on this, these two issues have to be disassociated as much as possible."

A second Polish official told DW that Warsaw does cooperate with Frontex and keeps both the EU and Frontex informed of the situation. Still, the official stressed, border management falls within the legal remit of national governments and is not an EU competence.

Fears of a humanitarian crisis unfolding

But with several deaths already recorded on the border, there are serious fears of a humanitarian crisis unfolding.

Civil society groups and press are barred from entering a zone delineated by Poland along its border with Belarus, and Brussels' attempts to send a delegation to inspect conditions on the ground have so far been rebuffed by Warsaw.

"The situation on the border has gone from bad to worse," Eve Geddie, director of Amnesty's EU office, told DW. "We're really concerned about people being ping-ponged back and forth and there are very worrying reports about treatment on both sides.

"People seek asylum in a moment of crisis and the asylum rules we have are precisely designed to deal with crisis moments. This is not an excuse to lower standards of protection," she said.

Amid the sanctions, statements and political saber-rattling, people are stranded on Poland's border with Belarus, and winter is approaching.