内容摘要："It is saying to the Sudanese Armed Forces: 'You can take Khartoum back, but you'll never be able to govern it. You can have Port Sudan, but you won't be able to govern it, because we will cause a security crisis for you so large that it will be ungovernable'... They want to unequivocally show that the war is not over until they say so."

"It is saying to the Sudanese Armed Forces: 'You can take Khartoum back, but you'll never be able to govern it. You can have Port Sudan, but you won't be able to govern it, because we will cause a security crisis for you so large that it will be ungovernable'... They want to unequivocally show that the war is not over until they say so."

They need to do that to get used to thinner oxygen levels at high mountain altitudes. Above 8,000m, known as the death zone, available oxygen is only a third of that present at sea level.But the four British men in the team did none of that.

"The team made a three-month acclimatisation programme in simulated altitude before coming to Nepal," Mr Furtenbach said.The simulated altitude was created in what is known as hypoxic tents from which oxygen is sucked out using a generator, bringing it to levels present at high mountain altitudes.Then the climbers inhaled xenon gas at a clinic in Germany two weeks before the expedition, said Mr Furtenbach.

"It helps to protect the body from altitude sickness," he said.Some researchers say xenon increases production of a protein called erythropoietin that fights hypoxia, a condition that occurs when the body can't get enough oxygen.

They say it does that by increasing the number of red blood cells that contain haemoglobin, which transports oxygen around the body, but this remains a disputed subject and many say further studies are required.

Some in the mountaineering industry have cautioned against the use of xenon gas.In all cases, the resources stay in Ukrainian ownership, even though the US will get joint access.

The inclusion of oil and gas has been seen as a softening of the Ukrainian position, since they were not in earlier drafts of the deal.Senior administration officials told reporters they believe that "more value" can be derived from these resources if the fighting ends quickly.

Ukraine has long aspired to join the European Union and accession talks formally began last June.There were some concerns in Kyiv that the resources deal could hinder Ukraine's ability to join the EU, if it gave preferential treatment to US investors, as Kyiv and Brussels already have a strategic partnership on raw materials.