Staff reporter
Investigators looking into the sinking of a South Korean warship in March have secured "decisive evidence" to prove that the frigate was sunk by a torpedo strike, a senior military official said Tuesday.
Traces of explosive collected from the wreckage are similar to those of a North Korean torpedo found in the West Sea seven years ago, the official said on condition of anonymity.
The investigation team discovered pieces of the propeller from the torpedo, he said.
The Ministry of National Defense neither confirmed nor denied the allegations.
The team, including experts from the U.S., Britain, Australia and Sweden, plans to announce the results of its investigation into the naval disaster Thursday.
Sources said the government has already drawn up a draft report on the cause of the Cheonan sinking and circulated it to security-related Cabinet ministers.
The report virtually points to North Korea as the culprit, the sources said.
Countermeasures include a large-scale joint submarine exercise of the South Korean and U.S. Navies, they said.
"A large-scale ROK-U.S. naval exercise would be one of the most practical countermeasures," a military source told The Korea Times. "It would not only help bolster the ROK-U.S. combined maritime defense readiness but also send a warning signal to North Korea." A U.S. nuclear-powered submarine may join the exercise, he added.
The government has been seeking to win support from the international community before referring the Cheonan issue to the U.N. Security Council (UNSC).
The government will brief ambassadors from about 30 countries, including those involved in the six-party talks, permanent UNSC members and EU member states, today on the results of the investigation and follow-up measures Wednesday, according to an official at the Ministry of Foreign Affairs and Trade.

어뢰 공격의 ‘결정적인 증거’ 확보
지난 3월 침몰한 전함의 원인을 찾고 있는 합동조사팀은 이 초계함이 어뢰공격을 받았다는 것을 증명해 줄 “결정적인 증거”를 확보했다고 고위 군관계자가 화요일 밝혔다.
이 관계자는 잔해에서 수집한 폭약의 흔적들이 7년 전 서해상에서 발견한 북한 어뢰에서 나온 것과 유사하다고 익명을 전제로 말했다.
그는 이 조사팀이 어뢰의 프로펠러 조각들을 건져냈다고 밝혔다.
국방부는 이에 대해 확인도 부인도 해주지 않았다.
미국과 영국, 호주 그리고 스웨덴 전문가들이 포함된 이 팀은 지금까지의 조사결과를 목요일 발표할 예정이다.