London — U.K. lawmakers on Tuesday warned of a growing threat from right-wing extremists and urged the military and police to tighten background checks. The parliamentary Intelligence and Security Committee said in its annual report that the phenomenon had been steadily increasing since 2017, with tech-savvy young men driving the rise. A growing number of young people under the age of 24 were now on the radar of the U.K. domestic security service MI5 investigating extreme right-wing terrorism (ERWT), it added. Of the 25 attacks which the security services and counter-terrorism police prevented between March 2017 and January 2020, eight...