Gates was not alone in his misgivings about NATO expansion. The ambassador to Moscow at the time was William Burns, a highly regarded diplomat who was well qualified for his post with his knowledge of Russian and prior experience in the country. The plan to bring Ukraine and Georgia into NATO alarmed him too. As he famously warned his boss, Secretary of State Condoleezza Rice, in February 2008, “Ukrainian entry into NATO is the brightest of all red lines for the Russian elite” from “the knuckle-draggers” in the Kremlin to “Putin’s sharpest liberal critics.” If Washington insisted on pushing Georgian membership, the ambassador predicted, the “prospects of subsequent Russian-Georgian armed conflict” would be high.
Link here.