Why was there no declaration of war before the attack pearl harbor?

Answer 1

There actually was a declaration of war, by Japan upon the USA, before Pearl Harbor. The Japanese tried to carefully plan everything so that the USA would officially be notified of the declaration of war exactly 30 minutes before the attack started.

However, the people who were supposed to translate the Japanese declaration, often called the "14 Part Message", into English took too long- the message was very long, and because it was highly classified, only certain people at the Japanese Embassy were allowed to read or translate it. By the time the message was translated and delivered to the US government, the attack (which lasted about two hours) had been finished for about an hour.

The other issue is that the wordy "declaration" wasn't really much of a declaration- it was somewhat vaguely worded and wasn't fully clear that the Japanese were declaring war. It mainly just listed grievances and at the end, declares that Japan will no longer negotiate with the US- which could be seen as a declaration of intent to go to war. Later that day, Japanese newspapers published the Emperor's official declaration of war on the US and UK- this time, it was not vague or ambiguous.

I'm including the ending of the 14 Part Message, so you can see for yourself:

Obviously it is the intention of the American Government to conspire with Great Britain and other countries to obstruct Japan's effort toward the establishment of peace through the creation of a new order in East Asia, and especially to preserve Anglo-American rights and interest by keeping Japan and China at war. This intention has been revealed clearly during the course of the present negotiation.

Thus, the earnest hope of the Japanese Government to adjust Japanese-American relations and to preserve and promote the peace of the Pacific through cooperation with the American Government has finally been lost.

The Japanese Government regrets to have to notify hereby the American Government that in view of the attitude of the American Government it cannot but consider that it is impossible to reach an agreement through further negotiations.

Answer 2

There actually was a declaration of war, by Japan upon the USA, before Pearl Harbor. The Japanese tried to carefully plan everything so that the USA would officially be notified of the declaration of war exactly 30 minutes before the attack started.

However, the people who were supposed to translate the Japanese declaration, often called the "14 Part Message", into English took too long- the message was very long, and because it was highly classified, only certain people at the Japanese Embassy were allowed to read or translate it. By the time the message was translated and delivered to the US government, the attack (which lasted about two hours) had been finished for about an hour.

The other issue is that the wordy "declaration" wasn't really much of a declaration- it was somewhat vaguely worded and wasn't fully clear that the Japanese were declaring war. It mainly just listed grievances and at the end, declares that Japan will no longer negotiate with the US- which could be seen as a declaration of intent to go to war. Later that day, Japanese newspapers published the Emperor's official declaration of war on the US and UK- this time, it was not vague or ambiguous.

I'm including the ending of the 14 Part Message, so you can see for yourself:

Obviously it is the intention of the American Government to conspire with Great Britain and other countries to obstruct Japan's effort toward the establishment of peace through the creation of a new order in East Asia, and especially to preserve Anglo-American rights and interest by keeping Japan and China at war. This intention has been revealed clearly during the course of the present negotiation.

Thus, the earnest hope of the Japanese Government to adjust Japanese-American relations and to preserve and promote the peace of the Pacific through cooperation with the American Government has finally been lost.

The Japanese Government regrets to have to notify hereby the American Government that in view of the attitude of the American Government it cannot but consider that it is impossible to reach an agreement through further negotiations.