Memo authorising the military to be deployed against anticipated protests is pre-emptive act – a first for the US

• LA protests – live updates

The Trump administration’s deployment of national guard troops to Los Angeles to intervene in civilian protests in the face of opposition from the Californian governor is a major escalation that risks the politicisation of the US military, armed service veterans are warning.

Former top military figures have told the Guardian that the decision to put up to 2,000 troops under federal control and send them into the streets of LA is a violation of the military’s commitment to keep out of domestic politics in all but the most exceptional circumstances. The last time a US president federalised the national guard against the wishes of a state governor was in 1965, when Lyndon Johnson deployed them to protect civil rights marchers in Alabama.