The government will surely use the diplomatic channels available.

政府肯定会采用现有的外交途径。

《柯林斯英汉双解大词典》

The date for the visit will be decided through diplomatic channels.

访问日期将通过外交途径商定。

youdao

This matter must be handled by going through diplomatic channels.

这件事情得经过外交途径才行。

youdao

And I think he realizes that the only way to resolve this really is through diplomatic channels.

NPR: Iran, Britain at Impasse over Captives

So far Iran has said nothing publicly and apparently given no clear response through diplomatic channels either.

BBC: Analysis: British yacht crew detained by Iran

In a gesture this week, the Egyptian government cut government-to-government contacts with Israel, though diplomatic channels remain open.

ECONOMIST: But there is little they can do