His foreign minister, Avigdor Liberman, blamed the leaders of a movement to boycott Israeli products manufactured in the occupied West Bank, saying that the killings were “the result of anti-Israeli and anti-Semitic incitement, expressed, among others, in the call to boycott Israel and Israeli products.”

“Hatred towards Jews has existed for thousands of years, and it reached its darkest hour in the European continent,” Israel’s economy minister, Naftali Bennett, wrote on Facebook. “In this generation,” he charged, “anti-Semitism has disguised itself as anti-Israel or anti-Zionist.”

As Belgium’s police searched for the suspect, the opinion pages of Israeli newspapers were filled with speculation about his motives. Writing on the English-language website of the daily Yedioth Ahronoth, Noah Klieger blamed “Muslim extremists and their many supporters,” and even claimed that European news organizations like the BBC were at fault for poisoning the atmosphere against Jews. Those channels, Mr. Klieger wrote, routinely broadcast “false and staged” news reports “presenting Israel as a terror state which engages in the coldblooded murder of children and women in the alleged occupied territories and sows havoc in the towns and villages in the Gaza Strip.”

Although some commentators connected the attack on Saturday to the success of xenophobic parties in European Parliament elections over the weekend, Amiel Ungar, a columnist for Haaretz who lives in a West Bank settlement, defended the right-wing populists. “The anti-Semitic climate in Europe did not develop in countries governed by Euroskeptical parties,” he wrote, “but in countries governed by the pro-European establishment.” As The Times reported in 2010 — when a delegation of anti-immigrant politicians from Germany, Austria, Belgium, Italy, Switzerland, Britain and Sweden toured West Bank settlements — anti-Islam leaders of the European right, like Geert Wilders, have made common cause with Israel’s settlers.

After the security-camera footage was released, however, another Haaretz columnist, the security writer Amir Oren, suggested that there might be a very different explanation for the attack.

Although Israeli officials told reporters that the killing of the couple from Tel Aviv was probably not related to their government service, Mr. Oren wrote that it seemed possible the shooting in Brussels “was not a hate crime or an anti-Semitic attack, but a targeted assault.” That possibility, he continued, “is strengthened by the video of the killer’s actions. He was caught by the cameras looking like a professional, as if this was a settling of scores. Not the assassination of accountants, but a battle in a covert war, though perhaps there was a misidentification of the intended victims.”