WASHINGTON — U.S. President Donald Trump ordered the declassification Thursday of the last secret files on the assassination of the late U.S. President John F. Kennedy, a case that still fuels conspiracy theories more than 60 years after his death. Trump signed an executive order that will also release documents on the 1960s assassinations of JFK’s younger brother, Robert F. Kennedy, and civil rights leader Martin Luther King Jr. “That’s a big one, huh? A lot of people have been waiting for this for years, for decades,” Trump told reporters as he signed the order in the Oval Office of the White House. After signing the order, Trump passed the pen he used to an aide, saying, “Give that to RFK Jr.,” JFK’s nephew and the current president’s nominee to become secretary of the Department of Health and Human Services. The order Trump signed requires the “full and complete release” of the JFK files, without redactions that he accepted back in 2017 when releasing most of the documents. “It is in the national interest to finally release all records related to these assassinations without delay,” the order said. Trump had previously promised to release the last of the files, most recently at his inauguration on Monday. The U.S. National Archives has released tens of thousands of records in recent years related to the November 22, 1963, assassination of President Kennedy but held thousands back, citing national security concerns. It said at the time of the latest large-scale release, in December 2022, that 97% of the Kennedy records — which total 5 million pages — had now been made public. The Warren Commission that investigated the shooting of the charismatic 46-year-old president determined that it was carried out by a former Marine sharpshooter, Lee Harvey Oswald, acting alone. But that formal conclusion has done little to quell speculation that a more sinister plot was behind Kennedy’s murder in Dallas, Texas, and the slow release of the government files has added fuel to various conspiracy theories. A gesture to RFK Jr. Trump’s move is partly a gesture to one of the most prominent backers of those conspiracies — Robert F. Kennedy Jr. himself. RFK Jr. said in 2023 there was “overwhelming evidence the CIA was involved” in his uncle JFK’s murder and “very convincing” evidence the agency was also behind the 1968 assassination of his own father, Robert F. Kennedy. The former attorney general was killed while campaigning for the Democratic nomination for president. Sirhan Sirhan, a Palestinian-born Jordanian, was convicted of his murder. Thousands of John Kennedy assassination-related documents from the National Archives were released during Trump’s first term in office, but he also held some back on national security grounds. Then-President Joe Biden said at the time of the December 2022 documents release that a “limited” number of files would continue to be held back at the request of unspecified “agencies.” Previous requests to withhold documents have come from the CIA and FBI. Kennedy scholars have said the documents still held by the archives are unlikely to contain any bombshell revelations or put to rest the rampant conspiracy theories about the assassination of the 35th U.S. president. Oswald, who had at one point defected to the Soviet Union, was shot to death two days after killing Kennedy by a nightclub owner, Jack Ruby, as he was being transferred from the city jail. Hundreds of books and movies such as the 1991 Oliver Stone film “JFK” have fueled the conspiracy industry, pointing the finger at Cold War rivals Russia or Cuba, the Mafia and even Kennedy’s vice president, Lyndon Johnson. King was assassinated in April 1968 in Memphis, Tennessee. James Earl Ray was convicted of the murder and died in prison in 1998, but King’s children have expressed doubts in the past that Ray was the assassin.