The Kremlin said on Wednesday that Russia would further expand its "buffer zone" inside Ukraine if Kyiv takes delivery of longer-range ATACM missiles from the United States that allow it to strike deeper inside Russia.

The United States is preparing a $1 billion military aid package for Ukraine, the first to be sourced from the yet to be signed Ukraine-Israel bill, two U.S. officials told Reuters on Tuesday.

When asked about the possibility that the package would include longer-range ATACM missiles, Kremlin spokesman Dmitry Peskov said Russia's stance on the subject - that it will be forced to expand what it calls a buffer zone in Ukraine if longer-range missiles are delivered - had not changed.