Australian airport security tightened after plot to down plane

Security checks at all major Australian airports have been ramped up following a counter-terrorism operation that foiled an alleged plot to bring down a plane. Four men were arrested in counter-terrorism raids on homes in the Sydney suburbs Saturday after authorities discovered plans for an attack to “bring down” an aircraft, prime minister Malcolm Turnbull said Sunday. Air passengers should expect delays caused by additional security measures at screening points. “Some of the measures will be obvious to the public, some will not be,” Turnbull said. Australian Federal Police commissioner Andrew Colvin said officers became aware people in Sydney were planning to commit a terrorist attack using an “improvised device.” The plot was believed to be inspired by Islamic State, Colvin added. <br/>