Today, however, the continued chaos in many European countries caused by immigration, and accompanying increase in crime -- including murder and rape committed by Islamist extremists -- appear to have proven the critics right.

Ever since the migrant crisis started to escalate in 2011 -- with the onset of civil war in Syria -- those who were critical of mass, unchecked immigration have been called "racists," "bigots" or "Islamophobes."

Turkish authorities repeatedly have threatened Europe with an influx of migrants. President Recep Tayyip Erdogan's threats should not be ignored.

A recent surge of illegal migrant arrivals has put the Greek city of Thessaloniki in crisis. "Dozens of migrants have turned Aristotelous square in the center of Thessaloniki to a makeshift camp," with many "sleeping in the open." Pictured: The Idomeni migrant relocation camp, near Thessaloniki. (Photo by Dan Kitwood/Getty Images)

Greece is currently facing a serious surge in undocumented migrant arrivals in the Evros region, an entry point for migrants illegally trying to enter the country from Turkey. Arrivals have roughly doubled since 2017, and Athens is holding Ankara responsible.

The influx from places such as Afghanistan, Pakistan, Syria, Iraq, Bangladesh and African countries into Turkey reportedly has been on the rise in recent months, with 1.5 million people from Muslim countries waiting on the Iranian border to enter Turkey. This has sparked fears in Athens that they could be heading for Greece.

According to a fact sheet released last month by the UN Refugee Agency (UNHCR), "Sea arrivals [in Greece] peaked this month with 4,000 people. Land arrivals through Evros also increased to 1,400."

As a result, the Greek city of Thessaloniki is in crisis. According to a recent article in The Greek Reporter, "Dozens of migrants have turned Aristotelous square in the center of Thessaloniki to a makeshift camp," with many "sleeping in the open."

This situation is likely to deteriorate even further, not only in Greece, but in the rest of Europe, with the massive number of new arrivals, particularly from Afghanistan, via Iran, into Turkey.

An investigative report in the Turkish daily Hurriyet, published in April, describes the way this is accomplished:

"Smugglers leave the Afghans and people from other countries, including children, on mountains. The illegals walk for kilometers through the border area... They all aim to go to Istanbul. But they first go to Erzurum, a city determined as the transit place.... Some then escape to Europe through Greece and Bulgaria, while others get involved in crimes, such as theft and prostitution, in Istanbul and are made to work as undocumented workers... "According to the data of Turkey's Immigration Authority, from the beginning of this year until March 29, 17,847 illegal Afghans have been caught. 9,426 Syrians, 5,311 Pakistanis, and 4,270 Iraqis have also been caught. The total number of illegals caught by police including those from other countries is 47,198."

In an interview in April with the Turkish daily Milliyet, Erdal Güzel, head of the Erzurum Development Foundation, said:

"It has reached the point at which the people entering Turkey illegally from and returning to Afghanistan has become as easy as [a Turkish citizen's] going from one Turkish city to another. They have learned the paths. "...According to their own testimonies, they take buses to Iran at night... They are kept waiting there... until the time is right. Some families are kept waiting with no food or water for 15 or 20 days. "They say they walk through the mountains. They all have the same story. Some say they walk through mountains for 4 or 5 days. They are told that 'even if one of you falls off a cliff, you will not make a sound.' ... Among them are pregnant women and blind people. In recent years, the migration traffic has escalated incredibly... Thousands of people are coming here... Human smugglers stuff these people in three-story trucks in which sheep are carried... What is strange is they come here at the cost of their lives. They enter Turkey and then want to go to Germany through Greece, Serbia and Hungary. They hit the road so zealously as if to say, 'Those who will die will die, and those who will stay alive will be here with us.'"

Human trafficking and people-smuggling are serious crimes and grave violations of human rights. According to a report by the US State Department:

"People who are smuggled can be extremely vulnerable to human trafficking, abuse, and other crimes, as they are illegally present in the country of destination and often owe large debts to their smugglers."

Nevertheless, it appears that a highly organized international network of various actors -- including smuggling and trafficking groups, international organizations and even governments, such as that of Turkey -- are involved or complicit in the mass illegal movement and abuse of a large number of people.

Turkish authorities repeatedly have threatened Europe with an influx of migrants. In November 2016, for instance, President Recep Tayyip Erdogan openly stated:

"When 50,000 refugees headed to Kapıkule [at the Turkey-Bulgaria border], you shrieked: 'What will we do if Turkey opens it border gates?' Look at me! If you go too far, we will open those border gates. Just know this."

Erdogan's threats should not be ignored. Among the smuggled migrants and refugees are ISIS supporters and other Islamist radicals. Also, many of the jihadi terrorists who participated in the deadly attacks in Manchester, Paris, Brussels, Berlin, Stockholm and St. Petersburg in recent years had connections to Turkey. Some were apprehended in Turkey; others either traveled there to cross into Syria to join ISIS or had lived there for a while. Turkey has been used routinely by Islamists as a route into areas of Syria and Iraq to join ISIS.

Ever since the migrant crisis started to escalate in 2011 -- with the onset of civil war in Syria -- those who were critical of mass, unchecked immigration have been called "racists," "bigots" or "Islamophobes."

Today, however, the continued chaos in many European countries caused by mass immigration, and accompanying increase in crime -- including murder and rape committed by Islamist extremists -- appear to have proven the critics right. It is urgent for European governments to find effective solutions to unfettered immigration. It is equally imperative for those governments to hold Turkey accountable for its part in the crisis.