Inside Britain’s Parliament, lawmakers jeered, booed, and stormed out of the House of Commons to protest the speaker’s handling of a vote calling for a cease-fire in Gaza. Outside, a crowd of pro-Palestinian demonstrators projected the slogan, “From the river to the sea,” on to the facade of Big Ben, drawing denunciations from those who view it as a rallying cry for the eradication of Israel. The chaotic scenes in London last week captured how Israel’s war in Gaza is reverberating far beyond the Middle East. From the United States to Europe, the brutal Oct. 7 attack by Hamas militants...