A depreciation of the yuan would have effects in some American companies (Apple, to name the most famous) whose income depends in large part the Chinese market. But what really would impact would be that other Asian exporting countries devaluing imitate the movement. As a result, the USD will appreciate against these currencies, which would reduce the profits of American multinationals and the recession could lead in this way to the US.
Therefore, in the Fed statement "recent economic and financial developments" as the cause of delaying the rate hike, feeds the suspicion that in that delicate balance of global forces that has become our world are cited, China also has to point its potential to export deflation to the world just scares even the US itself.
All roads go through Washington DC
In other words, Yellen must receive something like this message: "your raises rates we (China) devalue the currency, not just slashing corporate profits of your business, going into recession, but exporting deflation to the rest of world. "
The coincidence this week by Chinese President Xi Jinping, and Pope Francisco (important mediator in restoring relations between Cuba and the United States) in their respective journeys to the Americas, may help to improve relations between China and the US, for the benefit the rest of the world. Probably, we have to prepare for a somewhat longer scenario of low rates that many vaticinábamos before summer.