American officials have said they did not think a third meeting should be arranged unless a substantive agreement could be negotiated beforehand.

美方官员表示，他们认为已经没有必要安排第三次会谈，除非事先就能达成实质性的协议。

However, a system of imperial preference could not be established unilaterally, and Chamberlain was disappointed when a conference in Ottawa in July concluded with no substantive agreements to reduce trade barriers with Canada.

然而，帝国优惠制度不可能单方面建立起来，当7月份在渥太华举行的会议结束时， 张伯伦感到失望， 因为没有达成减少与加拿大贸易壁垒的实质性协议。