Pakistan, Sept. 7 -- Iran said it will step up efforts to tackle problems created by the US sanctions that are crippling its economy, while a senior Iranian official warned of a "painful response" if it comes under further attack. Six months after US-Israeli strikes against Iran, the war appears to be at a stalemate. A preliminary ceasefire accord reached in June has unravelled and little progress has been made in diplomatic efforts to get the peace process back on track. After a pause in military action for much of August, tit-for-tat strikes have resumed with US Central Command saying it hit three Iranian tankers on Saturday after Iran's Islamic Revolutionary Guard Corps launched ballistic missiles at two US Navy ships. Following the at...