The US is considering a request by Ukraine for long-range Tomahawk missiles, US Vice-President JD Vance has said.
However, Vance added President Donald Trump would be making the final determination on the matter.
Kyiv has long been calling for its Western partners to provide it with weapons that could hit major Russian cities far from the front line, arguing that they would help Ukraine seriously weaken Russia's military industry and bring the war to an end.
If the cost of continuing the war for Moscow is too high, it will be forced to start peace talks, deputy defence minister Ivan Havryliuk told the BBC.
Kremlin spokesman Dmitry Peskov played down Vance's suggestion, saying there was no panacea that can change the situation on the front for the Kyiv regime.
Whether it's Tomahawks or other missiles, they won't be able to change the dynamic, he added.
Tomahawk missiles have a range of 2,500 km (1,550 miles), which would put Moscow within reach for Ukraine.
While Vance remained ambivalent about Ukraine's request for Tomahawks in his remarks on Sunday, the US special envoy to Ukraine, Keith Kellogg, seemed to suggest Trump had already authorised strikes deep into Russian territory.
Vance and Kellogg's comments match the US administration's recent change of tone in regard to the war.
After repeatedly expressing scepticism that Ukraine could continue to hold its own against Russia, last week Trump said Kyiv could win all of Ukraine back in its original form – a shift that reportedly even surprised Ukraine's Volodymyr Zelensky.
On Sunday, a massive 12-hour strike involving hundreds of drones and nearly 50 missiles left four people dead in Kyiv and at least 70 injured.
Ukraine's Havryliuk told the BBC Russia was only going to further increase the intensity and severity of its aerial attacks.
To protect its skies from ballistic missiles, Kyiv has asked its Western partners for at least 10 units of Patriot surface-to-air defence systems which can detect and intercept oncoming missiles.
Earlier this month Moscow fired a record number of more than 800 drones and missiles – the highest since the start of the full-scale invasion of Ukraine in February 2022.
As well as being more frequent and intense, aerial attacks are also becoming more dangerous as Moscow is using new and more advanced drones to break through Ukraine's air defence systems.
Strengthening Ukraine's air defence system is seen as crucial for ensuring the security of Europe, especially following recent drone incursions into Polish airspace.
Ukraine is also focusing on domestically produced drones and missiles with long-range capabilities, as collaborations with Western allies continue to provide essential military support amidst ongoing war efforts.
