Brookings Fellow: If Trump Doesn't Draw a Red Line on Ukraine, Putin Will Only Get Bolder

Tensions flared up in Ukraine this week when Russian naval vessels rammed a Ukrainian tugboat in the Sea of Azov on Nov. 25. The sea, over which Ukraine and Russia share navigation rights, has become a flashpoint since Russia's annexation of Crimea in 2014. Over the last six months, Russian forces have been unlawfully detaining commercial ships seeking passage to Ukrainian ports on the Sea.