It was the National Security Agency that uncovered a 1973 plot to bomb New York City, a scheme since linked to a terrorist who is nearing release from prison, according to government documents and interviews. Khalid Al-Jawary, a Black September terrorist, placed two car bombs along Fifth Avenue and one near Kennedy Airport. The attack was meant to coincide with Prime Minister Golda Meir's arrival in the city. The bombs failed to detonate, and Al-Jawary quickly fled the country before being arrested nearly 20 years later. The case has gained increased attention since an Associated Press investigation provided new details about Al-Jawary's shadowy background. He's scheduled to be released Feb. 19 after serving only about half his 30-year prison sentence. But until now, it has been unclear how the authorities knew where to look for the cars. Shortly after Al-Jawary planted the bombs around March 4, the NSA intercepted a message revealing the location of them. "When we picked that one up, it was a shocker," said Jim Welsh, who served as an NSA analyst from 1969 to 1974. Declassified CIA records indicate the FBI and NYPD began looking for Al-Jawary's bombs at 7:15 p.m. on March 6, 1973 - not long after the NSA intercepted the message about the plot. The two bomb-rigged cars on Fifth Avenue were towed March 5 and were later found at impound yards. The third bomb at Kennedy Airport's El-Al cargo terminal was discovered early March 7 and disabled by Terence McTigue of the NYPD bomb squad. McTigue said the FBI never told him how they knew the car was at JFK, but he assumed they had obtained the information through an intercepted communication of some kind. The super-secretive NSA declined to comment. Welsh said someone transmitted the message using official Iraqi diplomatic communications in the US He believed it originated at the UN Iraqi mission in New York. Welsh said the message stated the bombs had been placed and gave their whereabouts. Welsh said the encrypted message was sent to the Iraqi foreign ministry in Baghdad, where it was relayed to the Palestine Liberation Organization's office. Iraq's specific involvement in the plot is not known, but the PLO routinely relied on friendly governments to facilitate communications during that era, said Matthew Aid, an intelligence historian who specializes in the NSA. Al-Jawary was known to use multiple passports, including an Iraqi one. One of his aliases was Abu Walid al-Iraqi. The FBI captured him in early 1991 after he left Baghdad to attend the funeral of a terrorist in Tunis. Declassified State Department documents say Iraq supported Black September, which intelligence officials believe was controlled by PLO leader Yasser Arafat. The NSA discovery of the plot is considered one of the early bright spots in the history of counterterrorism. "This story was well-known in the hallways of the NSA," said retired agency historian Robert J. Hanyok, who wrote an in-house article that included a reference to the "joint NSA-CIA-FBI effort." "It was definitely an early example of interagency cooperation," Hanyok said. The article was declassified in 2007. The NSA claimed it "thwarted" the plot, according to the Hanyok article. But it's still unclear to this day why the bombs did not explode. Welsh, now a businessman living in Oregon, said the success was especially important considering it came less than a week after an intelligence failure during an attack on the Saudi Embassy in Khartoum. The attack was also orchestrated by Black September and left three diplomats dead, including the U.S. ambassador to Sudan and the departing U.S. deputy chief of mission to Sudan. Welsh said the NSA had intercepted a call prior to the attack and alerted the State Department. But the warning failed to reach the American diplomats in time. Welsh said he believed the attacks in Khartoum and the attempted one in New York City were meant to be a "one-two punch" against the American government and show Black September could operate anywhere.