By Michael Isikoff and Mark Hosenball 
 
 U.S. intelligence officials appear to have obtained access to what could turn out to be a significant trove of phone numbers, photographs and documents detailing the links between Al Qaeda's leaders in northwest Pakistan and the terror group's increasingly menacing affiliate in Yemen, two counter-terrorism sources tell Declassified. 
 
 In late January, an Al Qaeda operative headed from Pakistan on his way to Yemen was arrested in the Persian Gulf country of Oman, a U.S. counter-terrorism official confirmed. 
 
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 There has been no public announcement of the arrest. But in a possible indication of the operative's importance, just a few days later, two postings on a jihadi web forum suggested that Al Qaeda leaders were worried and wanted their "commanders" to take immediate precautions. 
 
 The postings stated that the "captured brother" -- identified as a "field commander" named Abdullah Saleh al-Eidan who went by the name of "Barud"- - was "on his way back from Afghanistan" and had been turned over to Saudi authorities. 
 
 Even more noteworthy, the postings -written by a fellow Al Qaeda "brother" - reported that Al Eidan had with him 300 "important phone numbers" as well as pictures, names and documents from Afghanistan. 
 
 "The brother requested that this information reach the commanders in Yemen and Afghanistan as soon as possible," read one of the postings, which appeared on a web forum known as Fallujah Islamic Forum. "He also asked.the commanders to change their places of residence and mobile phone numbers as soon as possible." 
 
 While unable to confirm the specific figures in the web postings about Eidan's phone numbers and documents, the U.S. counter-terrorism official said that Eidan was in fact an Al Qaeda courier on a mission to Yemen and that his capture was providing "useful" intelligence about the terror group's operations.The official did not provide any details on how Eidan came to be arrested by authorities in Oman. 
 
 It is difficult to assess at this stage how significant the arrest of the Al Qaeda operative may be. But Evan Kohlmann, a counter-terrorism specialist who provides analysis for U.S. government agencies and who first spotted the web postings, told Declassified: "These kind of grabs are not all that common." "The idea that he would have personnel files on such a large cross section of Al Qaeda fighters is a remarkable gain," said Kohlmann. 
 
 At the same time, the capture of Eidan may suggest that the connections between Al Qaeda's central leadership and Al Qaeda in the Arabian Peninsula (AQAP)-as the group's affiliate in Yemen is called-- may be greater than U.S. officials have previously thought. 
 
 Just last month, when asked at a White House press briefing what was the most "shocking, stunning thing" he had learned from the administration's review of the Christmas Day bombing incident, John Brennan, President Obama's counter-terrorism advisor, replied: "Al Qaeda in the Arabian Peninsula is an extension of Al Qaeda core coming out of Pakistan. We had a strategic sense of sort of where they were going, but we didn't know they had progressed to the point of actually launching individuals here." 
 
 Just a few weeks later, Osama bin Laden released a brief audio message-from "Osama to Obama"-in which he praised the attempt to blow up Northwest Flight 253 over Detroit and called bombing suspect Omar Farouk Abdulmutallab a "hero." 
 
 At the time, U.S. security officials and others noted that bin Laden didn't actually take credit for ordering the bombing of the Northwest flight. 
 
 But the capture of Eidan-and his documents showing the apparent communication flow between Al Qaeda commanders in Afghanistan and Yemen-- could at least raise questions about whether bin Laden or his top confederates may have known more about it in advance than anybody initially suspected. 
 
 

 Washington (CNN) -- Some jihadist Web sites monitored by CNN are warning al Qaeda leaders that a recently captured field commander had more than 300 names and numbers plus important documents on him at the time of his arrest. 
 
 A U.S. counterterrorism official confirmed that Abdullah Saleh al-Eidan was captured in Oman in late January and is being held now in Saudi Arabia. The official, who is not authorized to speak on the record because of the sensitive nature of the information, would not comment on what intelligence has been gathered from al-Eidan. 
 
 But the official did say al-Eidan was caught as he was carrying information from al Qaeda "central" in the Pakistan/Afghanistan region to its affiliate in Yemen known as al Qaeda in the Arabian Peninsula. Oman, Yemen and Saudi Arabia are all located on the Arabian peninsula. 
 
 Al-Eidan has a background in explosives and is said to go by the name Barud, which is Arabic for a kind of explosive powder. The U.S. counterterrorism official said al-Eidan is not a senior member of al Qaeda, but he is "far from being just a foot soldier." 
 
 One of the jihadist Web sites posted a note on January 28 from an unidentified sender to al Qaeda leaders in Yemen and Afghanistan. It said that al-Eidan had been arrested in Oman and that "he had on his person more than 300 numbers and pictures and important names." 
 
 The message encouraged the leaders "to change their locations and mobile numbers as soon as possible." 
 
 Some experts question whether al Qaeda would have one individual carry that much important information. But if it is true, this could represent a possible gold mine for intelligence agencies. 
 
 It also may indicate a much tighter tie between al Qaeda central and its affiliate in Yemen than had been previously understood. 
 
 The story of al-Eidan's arrest was first reported in Newsweek. 
 

– Counterterrorism experts believe an al-Qaeda field commander captured last month is providing a major intelligence breakthrough. Abdullah Saleh al-Eidan's bust in Oman was swiftly followed by warnings on jihadi websites that he had the names and phone numbers of 300 "brothers" in his possession, urging militants to change their locations, CNN reports. Al-Eidan, an explosives specialist, was traveling from al-Qaeda's northwest Pakistan heartland to Yemen to meet with leaders of its offshoot al-Qaeda in the Arabian Peninsula. The documents in his possession are providing authorities with new details on the extent of the links between the two groups, sources tell Newsweek.