The Central Intelligence Agency told Ukrainian officials last summer that it had learned of what it thought was an aborted plot by the Ukrainians to attack the Nord Stream pipelines, and the agency reinforced its objection to any such operation.
In June 2022, Dutch intelligence officials shared information with the C.I.A. that they had learned the Ukrainian military had been planning an operation using divers to blow up one of the pipelines, according to U.S. and European officials. But the original tip by the Dutch, according to a U.S. official, was that Ukraine had already reconsidered and canceled the operation.
In reality, American officials now believe, the operation was not aborted but delayed, potentially with a different Ukraine-aligned group carrying out the attack.
Explosions destroyed parts of the pipelines, which carry natural gas from Russia to Europe, in September. The Ukrainian government denied responsibility for the attack.
But German investigators later learned that a group of Ukrainians had rented a boat, loaded it with explosives and attacked the pipeline. American intelligence agencies now believe the operation was carried out at least with the loose direction of the Ukrainian government, but they do not know who exactly planned the operation.
The information about the C.I.A. warning to Ukraine, and that it was Dutch intelligence officials who provided the original intelligence, was earlier reported by the German news outlet Die Zeit and NOS, the Dutch national broadcaster.
It is unclear which U.S. official delivered the message about the pipeline attack to Ukraine. It was not delivered by senior level officials, however, because the United States already believed that Kyiv had reconsidered the wisdom of the attack, according to the American official. It was also not clear how the Ukrainians responded to the Americans’ message.
The original warning collected by Dutch intelligence included details similar to the final operation, but it also differed in some key respects, according to the European official. The original intelligence said Ukraine intended to attack Nord Stream 1, whereas the actual attack was against both the older pipelines and the just-completed set, known as Nord Stream 2.
Dutch intelligence also reported that the plan would involve using fake Estonian passports, the European official said. At least some members of the group that European investigators believe carried out the attack used fake Bulgarian passports.
The original plan also involved using Ukrainian special forces personnel to rent a submersible and a boat to attack the pipelines, near a spot popular with divers, the European official said.
The C.I.A. was not able to corroborate the information the Dutch provided them last summer but nevertheless warned the German government that the pipelines could be attacked and then discussed the matter with Ukrainian officials.