The civil war in Syria is now in its fifth year and in this time over 4 million refugees have fled the country while nearly twice as many have become internally displaced.

Hundreds of thousands of these refugees, along with others fleeing threatened areas in the Middle East, Africa and elsewhere, are undertaking perilous journeys by land and sea after setting their sights on a better future in Europe.

This has resulted in the biggest refugee crisis the continent has experienced in decades. According to the Office of the United Nations High Commissioner for Refugees, there are nearly 4.1 million registered refugees from Syria. While some countries have opened their doors to varying degrees, others have hoisted barriers to the migrant tide.

Here is a look at how Syrian refugee crisis has unfolded in some key countries in the region:

LEBANON Government officials put the overall number of registered and unregistered refugees at 1.5 million. With an estimated population of about 4.5 million, Lebanon has the highest per-capita number of Syrian refugees, accounting for about 1 in 4 people in the country. It also currently holds half a million Palestinians remaining in refugee camps established six decades ago.

JORDAN Even though the country says it has taken in 1.4 million Syrians, the UNHCR counts 629,266 registered refugees. The high numbers accounting for almost 20% of the population, have taxed the small kingdom which is already struggling with strained resources such as energy and water.

TURKEY has taken in the most refugees of any country and is home to more than 1.9 million Syrians. About a third live in government-run camps near the border whereas others have dispersed.

ISRAEL is the only country sharing a border with Syria that has not taken in any Syrian refugees. Israel has extended humanitarian aid and medical treatment to more than 1,000 people injured in the fighting in Syria in recent years but has said it will not take in refugees.

QATAR, the UNITED ARAB EMIRATES and SAUDI ARABIA are increasingly criticized by rights organizations, which say the wealthy Persian Gulf countries have not offered to take in a single Syrian refugee. However, these nations have contributed to humanitarian aid.

GREECE despite not sharing a border with Syria,but the relatively short sail from Turkey has made it a prime destination for hundreds of thousands of migrants from Syria and other countries. Nearly 250,000 refugees have landed on Greek shores in 2015 after perilous sea journeys, overwhelming a number of islands where physical and administrative infrastructure are insufficient. While a small number have been given temporary housing in Athens, most refugees aim to use Greece as a land bridge through the Balkans and into Northern Europe.

ITALY is the second immediate destination of most Mediterranean migrant voyages and more than 110,000 refugees have arrived there this year. As with Greece, many opt to use the country as a bridge to wealthier, northern countries.

THE UNITED STATES has spent more than $4.1 billion since 2012 on what it calls the Syria Humanitarian Response, supporting food programs and refugee operations in Jordan and Lebanon. However, the U.S. has taken in only about 1,500 refugees from Syria, prompting criticism from rights organizations and others.

AUSTRALIA has firm, strictly enforced immigration policies, and it intercepts would-be migrants and asylum seekers at sea. However, Australia did take in 4,400 refugees from Syria and Iraq last year, and the government says it plans to increase that number.

GERMANY is the main destination for many hopefuls. From 2011 to this year, Germany received nearly 100,000 applications for asylum, but 100,000 more reached Germany last month alone as the crisis mushroomed. Europe’s strongest economy is bracing for 800,000 asylum seekers this year and cautions that other European Union partners must shoulder the burden or the entire open-border policy of the European bloc could be in danger.

SWEDEN is another coveted destination. Among European countries, it has taken in the most people relative to its size of its population and last year alone admitted 80,000 refugees, more than a third of them from Syria.

FRANCE said Monday that it would take in 24,000 refugees under a European Union-wide quota system that some member states are likely to reject.

BRITAIN said it would take in 20,000 Syrian refugees by the end of the current Parliament’s term in 2020.

Other European nations have been considerably less eager to embrace any refugees, most of whom are Muslim.

HUNGARY has begun erecting a border fence, and Prime Minister Viktor Orban has drawn criticism for comments about the need to preserve Europe’s Christian character.