The currency pair tried to take a firm run above the 160.00 mark earlier in the day, with the high touching 160.40. That was the highest point since 31 July, when the US and Japan acted in joint intervention to bolster defense of the Japanese yen currency.There was a bit of a pullback after but now we're seeing a quick drop in USD/JPY to 159.60 in the past 20-25 minutes:Is it perhaps a rate check from Tokyo again? Or is it just some nerves starting to show up as traders are afraid to overstep the boundaries and invite action from either Washington and/or Tokyo again?Either could be the case here and if it is the former, the effectiveness certainly is looking lesser this time around. And rightfully so.For all of Japan's intervention efforts since April, one can argue that they haven't executed them with much finesse.As mentioned before back in May:"The main thing about intervention isn't so much so as the money but more so about the signaling. You want enough players in the market to get that signal and amplify it, so as to get the idea that "we shouldn't mess with the MOF/BOJ". Otherwise, that signal can get lost in translation if there isn't enough liquidity follow through. And at the end of the day, it might just be passed off as more noise than an actual leading signal to traders."The timing of their intervention efforts is leaving a lot to be desired. But then again, they are up against a very tough backdrop as the fundamentals continue to run against the yen currency in just about every direction.And this week, we're once again seeing global bond yields surge higher to try and make a break for it. So, that's not quite a backdrop that you want to fight against as it just means we'll probably be revisiting this conversation in a matter of weeks. This article was written by Justin Low at investinglive.com.