Oksana Markarova, Ukraine's ambassador to the United States, addressed President Emmanuel Macron's recent suggestion that France would not act in kind if Russia were to carry out a nuclear attack on her country and emphasized that the "global response" to nuclear threats should be "very harsh" due to their gravity.  "We cannot rule out anything," said Markarova during an appearance on "Face the Nation" on Sunday, while speaking about the possibility that Russian President Vladimir Putin will use nuclear weapons amid the ongoing war in Ukraine.  Noting that Russian forces have taken control of Ukraine's Zaporizhzhia power plant, one of the largest nuclear plants in the world and the biggest in Europe, she acknowledged that a "big risk" exists as Putin threatens to launch a nuclear offensive. But, Markarova added, the issue of whether Putin will use nuclear force or not is "much bigger than Ukraine" as a decision to do so would break international weapons agreements and effectively endan