US national security adviser Jake Sullivan met with Turkish President Tayyip Erdogan’s chief adviser Ibrahim Kalin in Istanbul on Sunday and discussed “progress on NATO accession for Finland and Sweden,” the White House said in a statement. The two, whose meeting was unannounced to the media beforehand, also discussed Turkey’s condemnation of Russia’s annexation of Ukrainian territory. Turkey, a NATO member, has conducted a diplomatic balancing act since Russia invaded Ukraine on February 24. Ankara opposes Western sanctions on Russia and has close ties with both Moscow and Kyiv, its Black Sea…