The surprise visit followed what The Atlantic described as new U.S. intelligence that Putin could test NATO with a land incursion into the Baltics. The account provides no details about the intelligence, its sources, its timeline, or the evidence behind that assessment.
Estonia, Latvia and Lithuania are NATO members. Article 5 treats an armed attack on one ally as an attack on all and requires each member to assist; that assistance is not necessarily military.
The previous CIA-director visit to Moscow came in November 2021, when William Burns warned against invading Ukraine. Russia began its full-scale invasion about three months later.