NATO chief Jens Stoltenberg said any attack on the military alliance would be countered with “a united and forceful response,” after US presidential candidate Donald Trump invited Russia to do “whatever the hell they want” to NATO members not meeting their financial commitments. “Any suggestion that allies will not defend each other undermines all of our security, including that of the US, and puts American and European soldiers at increased risk,” Stoltenberg said in a statement on Sunday. “I expect that regardless of who wins the presidential election the US will remain a strong and committe…