Police in Berlin searched the apartment on Wednesday morning of four men believed to have links to the terrorist "Islamic State" (IS) network.

A team of over 50 police officers were at the scene in the neighborhood of Schöneberg. They suspect the four were plotting to "procure and deliver a considerable amount of assets in the form of night vision gear and binoculars for the jihad war of the terrorist group 'Islamic State' in Syria," police and public prosecutor in Berlin said in a joint statement, local newspaper "Der Tagesspiegel" reported.

The four suspects are not yet under arrest, but the investigation is ongoing, according to dpa news agency.

In mid-October, two alleged IS helpers - a 38-year-old Tunisian and a 28-year-old Russian citizen - were arrested in the western city of Aachen. They are said to have helped smuggle a person into Syria to support the terror group in the jihad it is waging in the region.

Terrorist suspect Ismail I. on the stand in Stuttgart

The apartment search in Berlin comes after Germany opened its second trial Wednesday for an alleged supporter of the IS group. The trial opened at the Stuttgart Higher Regional Court for a man, Ismail I., accused of fighting for IS. The 24-year-old son of Syrian and Lebanese parents told the court that he wanted to live a normal life. "It is horrible what I did. … My family was traumatized."

Using savvy recruitment and propaganda videos, IS continues to attract more followers from Western countries

According to the indictments, Ismail I. attended a militant training camp in Syria in mid-2013 and fought against Syrian government troops in Aleppo. He was then ordered back to Germany to procure equipment for the IS fighters.

There were two other defendants on trial: 38-year-old Sobhan A. and 34-year-old Ezzedine I.. They are said to have helped Ismail try to obtain battlefield supplies in Germany.

Ismail I. told the court he was driven to enlist with IS to avenge crimes against his family. He said one his brothers was killed in Lebanon in an attack by Syrian troops and that his grandmother had been repeatedly raped while in Syrian custody. Ismail's uncle was also persecuted, the court heard. He told the court how he had reeled from the loss of an unborn baby from his former Palestinian wife and that he was "demoralized" after they divorced, and eventually dropped out of a vocational school because of drug use.

Seeking help, he visited a mosque and was told to make a pilgrimage to the holy city of Mecca. The journey in 2013 took a detour after about two months when he entered Syria via Turkey, according to the indictment.

Kreshnik B. confesses in court

In Germany's first trial of a man suspected to have fought for IS abroad, 22-year-old Kreshnik B. whose parents are from Kosovo, admitted to fighting for the terrorist group in Syria in 2013.

"I saw it as my duty to fight against the suppression and tyranny" he told the court in Frankfurt.

He is expected to be sentenced in accordance with Germany's juvenile penal code.

Kreshnik B.'s trial opened on September 15

Domestic Islamist threat

With the number of Islamists on the rise in Germany, the president of the country's Federal Criminal Police Office (BKA) Jörg Ziercke has warned that "lone perpetrators" or "small groups" pose the greatest domestic threat.

In an Interview with the newspaper "Die Welt" published last Saturday, Ziercke warned that there were at least 1,000 people who were part of a growing Islamist terrorist scene in Germany. He added that 230 of them could be capable of "committing crimes on a substantial scale."

Last week, domestic intelligence also highlighted the rapid and "alarming" growth of the radical Islamic Sunni Salafist scene in Germany. "The group currently accounts for around 6,300 people," said federal intelligence chief Hans-Georg Maassen. "By the end of the year, it could reach 7,000. A few years ago, we counted just 2,800 Salafists."

German intelligence services can now also prove that at least 450 predominantly young Salafists have joined the jihad, the "holy war" in Syria and Iraq, with a large number of cases still going unreported. According to media reports, based on security sources, the actual number of Islamists who have left Germany could already top 1,800.

Rapper beheading video

Meanwhile, German authorities are investigating a video that appeared online on Tuesday night of a former rapper from Berlin, Denis Cuspert, aka. "Deso Dogg." The video appears to show the man holding up the head of a decapitated enemy of the jihadist group. It was not immediately clear whether or not Cuspert had committed the killing.

Denis Cuspert, who was thought to have been killed fighting with IS last month, has appeared in a recent IS propaganda video

He explains in the video in German that the victims had fought against IS and "that's why they received the death penalty."

The 39-year-old Cuspert grew up in the Kreuzberg neighborhood of Berlin, the son of a German mother and Ghanaian father. In 2002, he began his rap career, with lyrics frequently touching on themes of discrimination. The German news magazine Der Spiegel reported that, after spending time in prison for various offenses, Cuspert converted to Islam and joined the Salafist movement by 2010 at the latest.

sb/bw (dpa, Reuters)