U.S. President Donald Trump's decision to ramp up arms shipments to Ukraine is a signal to Kyiv to abandon peace efforts, Russia said on Thursday, vowing it would not accept the "blackmail" of Washington's new sanctions ultimatum.

President Trump reportedly questioned Ukrainian President Volodymyr Zelensky about whether Kyiv could blast Moscow and St Petersburg, but later indicated publicly that Russia’s capital should be off limits.

Russia has continued its nightly bombardment of Ukraine after President Donald Trump announced his decision to supply Ukraine with new military equipment and the White House's threats of further economic measures against Moscow.