The Defense Department has withheld approval for attacks as the White House has sought to entice Moscow to open peace talks.

Kyiv had long requested permission to use U.S. weapons to launch strikes deep into Russia before the Biden administration gave the go-ahead.

The US has blocked Ukraine from launching long-range missiles into Russia just days after President Donald Trump suggested it would be "impossible" to win the war without attacking Moscow. US officials told to the Wall Street Journal that a review mechanism was introduced earlier this year by the Pentagon that made it almost impossible for