When U.S. codebreakers here translated an intercepted secret radio cable from the Japanese Foreign Office in Tokyo to the embassy on Massachusetts Avenue Nov. 19, 1941, shock waves rolled across town, all the way to the White House.

"In case of emergency," the translated cable read in part, "the following warning will be added in the middle of the daily Japanese language shortwave news broadcast. This signal will be given in the middle and at the end as a weather forecast, and each sentence will be repeated twice.

"When this is heard, please destroy all code papers, etc. This is to be a completely secret arrangement."

At once, the nation's six Army and two Navy radio intercept stations were alerted to watch for Japan's message that trouble was about to start. Intelligence officers here made it a top priority for all radiomen to listen for the warning message from Japan.

The Japanese repeated the warning in a second secret message to Japan's embassies throughout the world the morning of Dec. 4, and that also was intercepted by U.S. codebreakers. It said:

"When crisis leading to worst arises, following will be broadcast at end weather reports: One, East Wind Rain, war with United States; two, North Wind Cloudy, war with Russia; three, West Wind Clear, war with Britain, including attack on Thailand, Malaya and Dutch Indies. If spoken twice, burn codes and secret papers."

On the eve of the 40th anniversary of the Japanese attack on Pearl Harbor, the question still persists: Why did the United States not heed these two messages as a warning that war with Japan was on its way?

An even more important question persists: Did the United States intercept a third message, what has been called a "winds execute message" announcing the start of war, and either ignore it or later cover it up in the aftermath of the Pearl Harbor attack to make it appear that the message was never received?

Fresh documents turned over to the National Archives by the supersecret National Security Agency, and The Pacific War, a new book by British author John Costello, are sure to fuel the controversy.

One of the Archives documents states flatly that on the night of Dec. 4, almost three days before the attack, the Japanese sent the "execute" message sounding the signal that a Japanese attack on the United States was imminent.

"I was on watch on the evening of Dec. 4 and picked up on schedule the Tokyo weather broadcast," former Chief Warrant Officer Ralph T. Briggs, a radio intercept operator at the Navy's Cheltenham, Md., station in 1941, told the National Security Agency in an interview it turned over to the Archives not long ago.

"We had been anticipating the tip-off code phrase for the impending diplomatic break with Great Britain: NISHI NO KAZE HARE, West Wind Clear. I soon discovered I had copied HIGASHI NO KAZE AME, which meant in Japanese, East Wind Rain. That meant a break with the United States."

Briggs said he teletyped the "East Wind Rain" message immediately to Navy intelligence headquarters in downtown Washington. As soon as he sent the teletype, he said, he made two carbon copies of the message and an entry in his log sheet of what he had done.

"That was the last time I ever saw the weather broadcast messages," Briggs told the NSA. "So, gentlemen, I lay it to rest. It that message is somewhere. Somebody took it out of there."

Briggs' charge of a cover-up is similar to a charge leveled after the war by Navy Capt. Lawrence Safford, chief of the Navy's Code and Signal Section, the unit to which Briggs said he teletyped the East Wind Rain message.

When the war ended, Safford told the joint congressional committee investigating Pearl Harbor that the message Briggs described had come into his office, been passed to higher-ups and been "spirited away and suppressed."

In the interview released by the NSA, Briggs tells of being called by Safford to appear as a witness on his behalf before Congress. Said Briggs:

"Before I had a chance to prepare myself to attend the hearings, I received a call from Capt. John Harper, commanding officer of the station, who stated that too much had already been revealed by the hearings. Then, he delivered his coup de grace. He said: 'You are not to confer with Capt. Safford any further. You are specifically prohibited from meeting with him . . . . ' "

The NSA declassified a second interview about the message. In it, Capt. George W. Linn, one of Safford's deputies, tells of the agony Safford suffered during the time he tried to persuade the Navy and Congress that a message stating "East Wind Rain" actually had come from Tokyo before the attack.

"Though I considered Capt. Safford's premise highly unlikely, he could have been right," Linn told the NSA. "Whether he was right or wrong, he was taking a course which was bound to damage him and his career."

Linn says that even without a valid "winds execute" message, the Japanese had tipped their hand that an attack of some kind was coming. Linn told the NSA that codebreakers translated a message from Tokyo Dec. 1 ordering embassies in Hong Kong, Singapore, Manila and London to destroy code machines. The same day, another message was intercepted ordering embassies around the world "to burn all telegraphic codes except two minor systems."

In his new book, Costello makes a strong case for the charge by Briggs and Safford that the Navy may have covered up reception of an East Wind Rain message that signaled the onset of war with Japan.

"What makes the incident more significant is not only that Briggs was ordered not to testify in support of Safford," Costello writes, "but that in 1960, when he was officer in charge of World War II communications intelligence in the Navy archives, he hunted extensively through volumes of signals but could not locate the East Wind Rain signal.

"However, he found his original log sheet where it is noted: 'All transmissions intercepted by me between 0560 thru 1300 . . . are missing from these files and . . . those intercepts contained the "winds message." ' "

Costello concludes about the East Wind Rain controversy:

"There is no hard proof that such a message was ever received, but there is the testimony of other persons--the operator who was convinced he received the signal--to suggest that yet another piece of the complex jigsaw puzzle of Pearl Harbor has still to be found.

"Even if the winds message had been passed on to Kimmel Rear Adm. Husband E. Kimmel, commander of the Pacific fleet at Pearl Harbor at the time of attack , it might not have prevented the catastrophe.

"But if indeed it was received and if the East Wind Rain signal 'went missing,' it indicates the lengths to which the most senior naval officers in Washington might have been prepared to go to cover up what could be construed as a fatal omission in not passing on vital intelligence."