The Independent's photo-history reaches the 1970s. This frank interpretation of the Truman doctrine, photographed in an American position during the invasion of Cambodia, may have been the popular reaction to Communist expansion, but US and South Vietnamese forces were finding it harder than ever to put theory into practice in South East Asia.

As the Vietnam conflict worsened, President Nixon attempted to defend the intensified bombing of the Ho Chi Minh trail in Eastern Laos and US offensives into Cambodia: "I would rather be a one-term president than a two-term president at the cost of seeing America become a second-rate power and accept the first defeat in its history." Such obdurance flew in the face of public opinion. The world had been horrified to learn late the year before of the massacre of over 500 Vietnamese civilians in the hamlet of Mylai.

The subsesquent trial by court martial of Lt. William Calley in 1970 - for his personal responsibility for at least 109 of these deaths - further fuelled international protest about US involvement.

The truculence of American foreign policy was reflected by the government's fatally heavy-handed reaction to the US anti-war movement. In May, National Guard soldiers at universities in Mississippi and Ohio fired into rioting crowds of anti-war demonstrators, killing six students. "When dissent turns to violence it invites tragedy," Nixon said, but support for the President was diminishing among Republicans and opposing Democrats. A day after the deaths of the student protestors, Nixon pledged to withdraw of all US troops from Cambodia and Laos within seven weeks.