BBC News with Gaenor Howells.

The">The oil company BP has begun its latest attempt to halt the

catastrophic

oil leak in the Gulf of Mexico. It's used underwater robots to remove a cap that was placed over the fractured wellhead last month. A new cap will be fitted later. However, a permanent solution to stopping the oil - two relief wells - is still weeks away. Madeleine Morris reports.

The

delicate

operation to replace one cap with a more tight-fitting one could take

up to

a week. During that time, oil will flow

unabated

into the Gulf of Mexico. But BP and the US Coast Guard believe it's worth the potential environmental damage. The current cap is gathering only around half the gushing crude. It's hoped the new one will be able to gather all of it ready to

siphon

up to three ships on the ocean surface. The Coast Guard said the switch was being made now because of a predicted week-long lull in the Gulf storm season.

President Obama has promised more help for war veterans suffering from post-traumatic stress disorder (PTSD). The aim is to make it easier for US veterans to receive federal benefits. In the past, they've had to provide records of a specific event that caused their condition. Under new rules, they'll only need to show that their conditions of service caused the disorder. President Obama called it a long overdue step.

"For years, many veterans with PTSD who have tried to seek benefits have often found themselves stymied. They've been required to produce evidence proving that a specific event caused their PTSD. Well, I don't think our troops on the battlefield should have to keep notes just