That trade should be well supported by money flows into Japeness Yen with all the geopolitycal tensions, especially thoose at east Ukraine.
Technically speaking 172,4-6 level worked as an support/ressistance so many times that it's just to good not to try an short here ;) There's also another view at this trade which would be to go short IF the price breaks below 171,9 green marked zone to the downside. Standard aproach is to go short at market price now with an 2 possible Stop Loss levels. The one presented on the chart is the safe one, just above last swing high. But for a better R;R ratio Stop Loss can be placed just above 25 August highs at 172,7 level, but that can be taken out by a small price pop up.