MIAMI, Dec. 17 - The number of Cubans intercepted at sea while trying to reach the United States is at its highest level since tens of thousands took to the Florida Straits on makeshift rafts and in small boats in the 1994 exodus sanctioned by President Fidel Castro. The sharp rise - and an increase in clashes between would-be immigrants and the Coast Guard - are inflaming tensions over a policy enacted in response to the 1994 migration that allows Cubans without visas to stay if they reach American soil but turns back those caught at sea. The "wet foot,...