Following a wave of terrorist attacks in France, French Prime Minister Manuel Valls is considering prohibiting foreign funding for mosques in the country and has suggested adopting a new model for relations with Islam. The measures come in part as a response to growing public frustration with the French government's security failures leading up to the attacks. Over the weekend, French newspaper Le Monde published research indicating that the vast majority of terrorists that took part in attacks throughout France were known to security services, and some of them had even been arrested and released. As an example, the report named Normandy attacker Adel Kermiche, 19, who slit a priest's throat last week. He had been accused of terrorist activity and of trying to go to Syria in the past and was released from custody until his trial. Kermiche, who wore an electronic tracking device, was one of two attackers at the Normandy church. His partner in the murder, Abdel-Malik Nabil Petitjean, was also known to the French authorities as an Islamist operative. Valls told Le Monde that Kermiche's release was "a failure that we must admit." According to him, French judges ruling on terrorism cases "must take a different case-by-case approach, given the jihadis' very advanced concealment methods." He added that he was "open to the idea that -- for a period yet to be determined -- there should be no financing from abroad for the construction of mosques," and suggested that imams should be trained exclusively in France. Valls said that French Interior Minister Bernard Cazeneuve was developing a new model for France to relate to Islam. Some have called for both he and Cazeneuve to step down from their posts in the wake of the recent attacks. Meanwhile, French police and military reinforced their presence in the port city of Calais over the weekend following warnings that Islamic State terrorists may be planning an attack on boats bound for the United Kingdom. Likewise, throughout Europe, security has been increased in an effort to prepare for and thwart potential terrorist attacks. Security preparations were especially noticeable in Belgium, Holland and Germany over the weekend. In Munich, crowds were evacuated from the Pasing Arcaden shopping center and Pasing railway station on Saturday following a bomb threat. The incident followed a shooting attack at a Munich shopping mall carried out by a German-Iranian teenager about a week earlier. Munich police said the decision to evacuate the area was a "precautionary measure." Earlier on Saturday, security was heightened at Schiphol airport near Amsterdam also due to an attack warning. The heightened security did not affect incoming or outgoing flights. On Friday, security forces in Belgium arrested two brothers suspected of planning an attack in the country. One of the brothers, named as Nourredine H., was indicted Saturday. The other, named as Hamza H., was released unconditionally. The Belgian prosecution did not state specifically where the planned attack was to take place. Thus far, no links have been found between the brothers and the terror cell that carried out the March bombing attacks in Brussels. According to Belgian reports, Nourredine H. was known to local authorities for assisting people interested in going to Syria.