それは外交辞令だ。の英語

Those words are mere diplomatic niceties.

I am cheerful and diplomatic.

I will ask the person in charge of foreign affairs about that matter.

He is thinking that he wants to be a diplomat.

He wants to become a diplomat.

I will become a diplomat, no matter what.

I will certainly become a diplomat.

He is a past master of diplomacy.

He is a diplomat―in the diplomatic service.

She said it just to be polite.

They don't know diplomacy.

They don't understand diplomacy.

He's good at the game of diplomacy.

to make a mistake in diplomacy―commit a diplomatic blunder

He has become a diplomat―entered upon a diplomatic career.

he answered very diplomatically

diplomatic intercourse

strained diplomatic relations

The two countries do not have diplomatic relations.

He aspires to diplomatic honours.

rupture of diplomatic relations

normalize diplomatic relations with ...

with diplomacy

the tension of diplomatic relations―strained diplomatic relations

strained diplomatic relations―the tension of diplomatic relations

He got a post as a diplomat.

to break off diplomatic relations

go into the diplomatic service

He is an incipient diplomat―an embryo diplomat―a diplomat in embryo.

That is out of the question.