On Tuesday, U.K. Prime Minister Keir Starmer hailed the possibility of NATO-backed security guarantees as a “breakthrough,” noting that the U.S. was now working “at pace” with 30 or so other countries, which he called a “coalition of the willing,” to help Ukraine.

Russia said on Wednesday attempts to resolve security issues relating to Ukraine without Moscow's participation were a "road to nowhere," sounding a warning to the West as it scrambles to work out guarantees for Kyiv's future protection.

T wo German fighter jets were scrambled to the Romanian-Ukrainian border on Tuesday night in response to a Russian drone attack in the frontier region, Romania's Defense Ministry said in a statement.