Hundreds of migrants are stuck in freezing temperatures on the Belarusian border with Poland trying to get into the European Union as EU capitals and Minsk accuse each other of causing the crisis and of endangering lives.
Some migrants have already died and there are fears for the safety of the rest as bitter winter conditions settle in.
Poland and other EU member states say Belarus is encouraging the migrants to cross the border into the EU in revenge for sanctions slapped on Minsk over human rights abuses, a charge president Alexander Lukashenko's government denies.
Relations between the EU and Minsk deteriorated sharply after Lukashenko, in power since 1994, claimed victory in a presidential election last year. His opponents, backed by the West, say the vote was rigged and staged mass street protests that Belarusian security forces then violently quashed.
Why are the migrants in Belarus?
Large groups of people fleeing conflicts and poverty in the Middle East and elsewhere started flying to Minsk this spring. They then travel to the border with EU members Poland, Lithuania or Latvia by taxi, bus or cars provided by human smugglers and try to cross.
If successful, they request asylum in Poland or contact family members or smugglers who can drive them to western Europe, the final destination for the majority.
Most migrants use travel agencies across the Middle East which partner with Belarusian companies to book tourism packages that usually include visa, flight and accommodation. Agencies secure visas at Belarusian consulates from Ankara to Beirut which have been regulating the number of visas issued.
As more migrants learn about the Minsk route through smugglers, social media and online advertisements, Poland's Border Guard services have reported rising numbers of attempts to cross the border.
The price of the whole journey varies and can reach up to about $14,000 (€12,000). In October, Minsk restricted the number of travel agencies in Belarus allowed to deliver tourism invitations, and smugglers as well as agencies have reported a rise in prices.
What is Lukashenko's strategy?
Warsaw and Brussels say Lukashenko is deliberately pushing migrants into the EU in retaliation for sanctions against him and other top Belarusian officials, even helping them by providing tools for cutting through the border fences.
Polish authorities have made available documents, including official invitations, visa applications and hotel bookings, which they say show the role played by Belarusian travel agencies in inviting migrants to Minsk.
Lukashenko's government, which is backed by Russia, has denied manufacturing the crisis and blames Europe and the United States for the plight of people stranded at the border.
How are Poland and the EU responding?
Poland has said it would build a wall along the stretches of the border targeted by migrants and has already erected a barbed wire fence along the most vulnerable parts.
In September, Warsaw also declared a state of emergency in a 3km strip along the border. In early November, the Interior Ministry said it had drafted more police, border guards and volunteer militia personnel into the area.
The European Commission has called on other EU governments to approve tougher sanctions against Belarus for trafficking migrants and to blacklist airlines that fly them to Belarus from the Middle East and other hotspots.
The Commission has offered to help Poland with reinforcements from the EU border guard services, Frontex, as well as to help with background checks of asylum seekers and migrants.
A small team of British armed forces personnel was deployed to Poland on Friday to provide engineering support to Polish forces.
Meanwhile, Turkey banned Syrian, Yemeni and Iraqi citizens from flights to Minsk on Friday, potentially closing off one of the main routes that the EU says Belarus has used to fly in migrants by the thousand to engineer a humanitarian crisis on its frontier.
