The Wall Street Journal reports: Belgian police rounded up six more people they said were connected to this week’s terror attacks, as the government on Thursday acknowledged high-level counterterrorism failings.

The justice and interior ministers both offered to resign a day after Turkey disclosed it had warned Belgium last summer that it suspected Ibrahim el-Bakraoui, one of two suicide bombers at the Brussels Airport, had ties to Islamic State—to no avail.

Mr. Bakraoui and his younger brother, Khalid, both from Brussels, were known to Western intelligence and were on at least one U.S. watch list, said a U.S. official. It couldn’t be immediately learned how they were classified on the list.

While U.S. often shares names on its various watch lists, it isn’t known whether they did in this case. The Belgian government has so many people to surveil, it is difficult for them to prioritize who might be the most urgent.

Separately, the Belgian federal prosecutor’s office said that an investigating judge on Dec. 11 had issued international and European arrest warrants for Khalid, the subway bomber. The judge specializes in terrorism and is in charge of the Paris attack investigation in Belgium.

On Wednesday, the same prosecutor said neither brother had criminal records linked to terrorism. The office didn’t offer further details Thursday.

Prime Minister Charles Michel refused to accept the resignations of his ministers. Jan Jambon, the interior minister, told a Belgian broadcaster that Mr. Michel cited the “situation of war.”

The most urgent question for investigators is how many more members of the terror network remain at large. U.S. officials said Islamic State’s strategy in Europe includes having fighters trained in Syria tap into networks of radicalized, disgruntled youth.

The Belgian federal prosecutor’s office said late Thursday that it had arrested six people and conducted searches in various Brussels neighborhoods including Schaerbeek, where at least one of the attackers lived.

In France, police also carried out counterterror raids in a Paris suburb on Thursday and detained a man who was in the “advanced stage” of planning a terrorist attack, French Interior Minister Bernard Cazeneuve said.

No link was immediately established with the recent attacks in Brussels or in Paris on Nov. 13, he said. [Continue reading…]