Washington says prepared to do more as Moscow warns countries ‘on verge of military clash’

‘America First’ president suddenly dons uniform of world’s policeman

Yet Kremlin language tempered by realisation Moscow needs Trump for Assad deal

Trump not seen as willing to intervene deeper in the conflict despite missile attack

Officials applaud military intervention after hands-off policy of Obama administration

Missiles hit air base the US believes carried out gas attack that killed more than 70

Show of strength does not commit Washington to a particular course of action

Politicians say attack raises spectre of direct military confrontation with America

Powerful cleric among those who will contest next month’s crucial election