A major airport in northern Japan reopened today after bomb squads barricaded the area around an unexploded bomb from World War II.

sendai airport

Flights resumed at Sendai Airport after military troops worked through the night to pile sandbags around the 250-kilogram bomb, which was uncovered during construction near a runway two days earlier.

The airport, a regional hub for northeastern Japan, was closed all day Tuesday, with 92 flights cancelled.

The rust-covered bomb was surrounded by sandbags and the area around it sealed off so that flights could start up again. Officials said the condition of the detonator wasn't clear, the fear that it would go off by accident was low.

WW II bomb discoveries not rare

Sendai Airport was closed for months due to severe damage from last year's tsunami. The bomb was uncovered in construction related to its restoration. Officials said it could take a week to actually dispose of the bomb, which would have to be transported elsewhere or readied for a controlled detonation onsite.

The United States heavily bombed Japanese cities during WW II, and finding unexploded bombs is not unusual, even 67 years after Japan's surrender. Dozens of duds are uncovered in Tokyo each year, and even more are found on the southern island of Okinawa, the site of the most intense fighting during the war.

Many bombs are found at construction sites. Their rusty condition can make them prone to detonate when moved, but injuries are rare. Experts say it could take several decades to remove all of the unexploded ordnance.

Last week, hundreds of residents in central Tokyo were evacuated so that bomb squads could remove a 220-kilogram dud buried there.