Croatian Prime Minister Zoran Milanovic is seen as he leaves the Elysee Palace in Paris, October 10, 2013. Reuters It did not take long for old wounds to re-open in the Balkans.

Since Hungary sealed its border with Serbia nine days ago, about 50,000 refugees have entered Croatia.

To try and stem the flow of people coming through, Croatia closed all but one of its border crossings with Serbia and closed the border to cargo traffic.

In retaliation, Serbia banned Croatian cargo traffic from entering the country as well as the import of Croatian goods, the Associated Press reports. Croatia then barred any vehicles with Serbian license plates from passing the border.

According to witnesses, Serbian citizens were also being turned away at the border, Reuters reports. Croatian police said it was due to a computer glitch.

After Serbia implemented the ban on Croatian goods and cargo traffic, Croatian Prime Minister Zoran Milanovic said they had to react.

"I planned to open the border ... but now I won't," Milanovic said, "We have to react to this now."

Things quickly escalated from there as ministers from both countries started firing accusatory comments at each other.

Europe's refugee crisis BI Graphics

The Serbian Foreign Minister said in a statement that the measures were discriminatory against Serbians.

"In their discriminatory character, they can only be compared with measures taken in the past, during the fascist Independent Croatia,” and further compared them to actions taken by the Croatian regime during World War II, the AP reports.

The situation risks wrecking reconciliations between the two countries that were 15 years in the making. Relations between the two countries are now at their lowest point since 2000. From 1991 to 1995, Croatia was at war with Serbian rebels backed by Belgrade as the country fought for its independence from Yugoslavia.

Croatia says it cannot cope with the influx of refugees and is angry that Serbia is simply sending them to their border rather than redirecting them to Hungary or Romania.

Migrants push policemen during a stampede to board buses in Tovarnik, Croatia September 17, 2015. Thomson Reuters

"What we've asked (for) from the day one ... is to avoid the situation where thousands of people enter through the crossing, which is not manned by a single Serbian policeman and no one controls it," Croatian Interior Minister Ranko Ostojic said, according to the AP.

This escalating diplomatic spat shows how much the hundreds of thousands of refugees coming into Europe are already impacting the region. It also highlights the financial ramifications, as it is estimated that the bans are costing both countries about $1.1 million a day.

This trade war also underscores the necessity for the European Union to set up a cohesive and inclusive plan to respond to this humanitarian crisis which has been ripping into an already fragile Europe.