My two cents: 
The paragraph could use some commas, or parentheses:

>The setbacks to the Minsk deal, since the rebels disavowed it by taking a strategic town they said was not covered by the truce, have prompted new calls for U.S. President Barack Obama to give Kiev lethal weapons to defend Ukraine.

>The setbacks to the Minsk deal (since the rebels disavowed it by taking a strategic town they said was not covered by the truce) have prompted new calls for U.S. President Barack Obama to give Kiev lethal weapons to defend Ukraine.