Before the recent restrictions imposed by the U.S., a rising tempo of Ukrainian strikes inside Russia – such as those targeting stores of ammunition — relieved pressure on Ukrainian troops on the front lines. It is one of the reasons Russia’s advances in eastern Ukraine have slowed in recent weeks, analysts say.

Officials say the halt in assistance is a warning to the Ukrainians of the consequences of not cooperating with the president.

The rupture of U.S. intelligence-sharing with Ukraine, confirmed by the CIA director, involves the targeting of longer-range strikes inside Russia.