Twin car bombs and multiple other attacks killed four NATO soldiers and 10 Afghans last evening, taking foreign troop deaths this year well above the level for the first two months of 2009.The NATO deaths in southern and western Afghanistan mean 105 foreign soldiers have been killed this year — twice the number in the same period last year. A string of bomb blasts struck the south within 24 hours in an increase in Taliban-linked violence more than two weeks after thousands of US-led troops launched a major offensive in Helmand province. The attacks highlighted the threat posed by the militia across much of the nation and emphasised the challenge faced by US and NATO troops taking part in a military surge aimed at ending the eight-year war.