First exchange of fire between two countries in more than a month sends oil prices rising 3%

'We're going to hit them hard,' US president says; Tehran source downplays flare-up, says it's 'limited and contained'; US vows to persist with economic pressure campaign

NEW YORK/LONDON, Aug 31 : Bond yields rose and stocks fell on Monday as oil prices jumped more than 2 per cent, with a resumption of military clashes between the U.S. and Iran…