Manchester concert suicide attack prompts security rethinks worldwide

Commuters make their way down Trinity Way near the Manchester Arena in Manchester, Britain May 23, 2017. REUTERS/Andrew Yates

TOKYO/SINGAPORE (Reuters) - Countries from the United States to Japan and Singapore are considering tightening security ahead of major theatre and sports events following a suicide bomb attack in Britain that killed at least 22 people.

Britain was on its second-highest alert level of "severe", meaning an attack by militants is considered highly likely, after the suicide bomb blast at the end of a concert by U.S. singer Ariana Grande in Manchester on Monday.