#Religion: German political leaders and national security officials knew that Islamic State jihadists were entering Europe disguised as migrants but repeatedly downplayed the threat, apparently to avoid fueling anti-immigration sentiments, according to an exposé by German public television.

German officials knew as early as March 2015 — some six months before Chancellor Angela Merkel opened German borders to more than a million migrants from the Muslim world — that jihadists were posing as refugees, according to the Munich Report (Report München), an investigative journalism program broadcast by ARD public television on January 17.

More than 400 migrants who entered Germany as asylum seekers in 2015 and 2016 are now being investigated for links to Islamic terrorism, according to the Federal Criminal Police (Bundeskriminalamt, BKA).

The revelations come amid criticism of U.S. President Donald J. Trump's plans to suspend immigration from select countries until mechanisms are in place to properly vet migrants entering the United States. The German experience with jihadists posing as migrants serves as a case study on errors for other countries to avoid.

Based on leaked documents and interviews with informants, the Munich Report revealed that German authorities knew in early 2015 that Walid Salihi, an 18-year-old Syrian who applied for asylum in Germany in 2014, was recruiting for the Islamic State at his asylum shelter in Recklinghausen, but they did nothing. Some six months later, a search of Salihi's accommodation produced a shotgun. Salihi was not deported.

It later emerged that between 2011 and 2015, Salihi had used seven aliases to apply for asylum not only in Germany, but also in Austria, Italy, Romania, Sweden and Switzerland. He had also been charged in several countries with a laundry list of crimes, including physical assault, robbery and weapons offenses.

In February 2014, for example, Salihi was arrested for sexually assaulting women at a discotheque in Cologne. That same month, he physically assaulted a homeless man, attacked a random passerby and attempted to strangle a fellow resident at his asylum shelter. Police later traced his cellphone to downtown Cologne on December 31, 2015, when hundreds of German women were sexually assaulted by mobs of Muslim migrants.

On January 7, 2016, Salihi stormed a police station in the 18th district of Paris while shouting "Allahu Akbar." He was carrying a butcher knife, an Islamic State flag and was wearing what appeared to be an explosive belt. Police opened fire and shot him dead.

A former roommate described Salihi: "He was very aggressive, especially when it came to religion. To him, all unbelievers were worthless and had to die."

Salihi was not an isolated case. According to the Munich Report, in early 2015 American intelligence agencies warned German authorities that Islamic State jihadists posing as migrants were making their way through southern Europe with the aim of reaching Germany.

The warnings, however, were ignored, and in the summer of 2015, German authorities allowed hundreds of thousands of migrants, many lacking documentation, to enter Germany without a security check.

At the time, leading German security experts insisted that the Islamic State would not send jihadists to Europe. In October 2015, for example, Holger Münch, President of the Federal Criminal Police (Bundeskriminalamt, BKA), said: "We do not have a single case yet in which it has been confirmed that members of a terrorist group from Syria or Iraq have come here to Germany specifically to commit attacks."

Münch also said: "If you look at the risks you face by coming to Germany via the Mediterranean Sea, I think there are simpler ways to get here if you plan to do so, and you do not need a stream of refugees."

Gerhard Schindler, President of the Federal Intelligence Service (Bundesnachrichtendienst) said: "It is unlikely that terrorists will use the dangerous boat route across the Mediterranean to get to Europe."