宣戦布告の理由は判明していない。の英語

The reason for declaring war is not certain.

the reason that war was declared

The motive for the murder is not yet known.

The motive for the murder isn't yet known.

The cause of that outbreak is unknown.

The cause of the accident is unknown.

The cause of the fire is not known.

The cause of the fire isn't known.

The cause of the fire is still unknown.

The cause is unknown.

The cause of the accident is still obscure.

The cause of the fire was unknown.

It is not known exactly what causes clubfeet.

the reason for their actions is unclear to this day

At this point in time we do not know what the cause is.

The causes of that still haven't been solved.

It was reported that the root cause was unidentified.

The cause is unclear

The accused maintained his innocence.

But so far the cause hasn't been traced.

The cause of the malfunction is still unknown.

At present, the cause of the disease is unknown.

At present the cause of the disease is unknown.

The cause is not yet ascertained.

The real cause of his death is unknown.

The cause of the accident is not known to us.

No speculation has taken place concerning the motives.

the petitionary procedure had a quality of indecisiveness

This disease has no known cause.

The origin of the fire is unknown.