That's the problem lawmakers are wrestling with amid hearings and federal investigations of the Upper Big Branch mine blast in West Virginia and the BP oil rig collapse in the Gulf of Mexico.

在西弗吉尼亚州煤矿爆炸和英国石油公司在墨西哥湾的钻井平台漏油事故的听证会和联邦调查中，这就是国会议员们正在努力解决的问题。

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At least one vehicle at the front of the convoy was then hit by a land-mine blast before as many as 200 suspected rebels opened fire, they added.

BBC: India probes deadly Maoist ambush in Chhattisgarh

Specialist mine rescue crews, ambulances and helicopters rushed to the mine as soon as the blast was reported.

BBC: New Zealand miners missing after explosion

Along with jammers, troops use air surveillance, robots, blast-resistant vehicles and mine rollers as countermeasures.

CNN: Jamming systems play secret role in Iraq