More than 1 million refugees entered Europe during the last year, the largest movement of migrants in the region since World War II.

The milestone was confirmed by the International Organization of Migration (IMO) on Monday, which said the vast majority of “irregular migrants” entered Europe through Greece, an often-treacherous voyage that has seen heavy death tolls particularly among children.

The bulk of the refugees have poured out of Syria, escaping a years-long civil war. Others continue to arrive from Africa and South Asia, fleeing poverty and oppression.

According to the IMO, 999,745 people have reached Europe over the Mediterranean Sea since January, with only another 3 percent traveling by land.

More than 800,000 have entered through Greece, 150,000 through Italy, and nearly 30,000 through Bulgaria, according to the organization’s statistics.

And the death toll continues to climb. At least 3,692 migrants died this year during the voyage, the IMO says, and a growing number of the fatalities are among children or infants. In December alone, six of 15 bodies washing up on Greek shores were children, according to the Greek Coast Guard.

“We know migration is inevitable, necessary, and desirable,” says IMO director general William Lacy Swing in a statement. “But it’s not enough to count the number of those arriving – or the nearly 4,000 this year reported missing or drowned. We must also act. Migration must be legal, safe and secure for all – both for the migrants themselves and the countries that will become their new homes."

But Europe has struggled to respond to the wave of people entering the region. By July, more than 185,000 people applied for asylum in the European Union, and numbers will continue climbing.

The scenarios playing out in the EU and across the world are a part of the largest migration in human history. Nearly 60 million people were displaced by 2014, according the United Nations High Commissioner for Refugees. That’s one out of every 122 people on Earth.

“This is a trend, not a blip,” David Miliband, executive director of the International Rescue Committee in New York, tells the Monitor.

Yet EU governments have differed over how to respond to the flow of people. Some have opened their doors while others are building fences. Many migrants are trapped in limbo, unable to work and unsure of where to go.

Hungary began constructing a 13-foot fence covered in razor-sharp wire along its border to deter refugees from coming in.

The surge in refugees has also had political repercussions across Europe, with many voters in Britain, Spain, Greece, and Germany moving further to the political right or left and beginning to pull populist parties into the mainstream.

Turkey has also become a haven for Syrians outside of the EU, with 2.2 million now living there. More than 1 million Syrians have fled to Lebanon and 633,000 to Jordan, the Guardian reports.

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But many continue to push in to Europe, where they hope to gain citizenship through laws created under the 1951 United Nations convention on refugees.

“In Jordan, life is so difficult,” one Syrian student told the Guardian after arriving this week in Greece. “There’s no work. I can’t go to university. There’s no hope. And in Turkey it’s the same thing: no work and no hope.”