The UK defence ministry claims Russia has used a "significant proportion" of its recently built-up long-range missile stockpiles after days of heavy strikes in Ukraine.
"Since 29 December, Russia has increased the intensity of its long-range strike operations against Ukraine," it said.
"Its forces have committed a significant proportion of the stock of air-launched cruise and ballistic missiles they had build up over recent months."
The MoD did not provide any statistics or figures to back up its findings in its latest intelligence report.
It also claims the strikes were aimed at Ukrainian defence industry targets.
"This contrasts with its major attacks last winter which prioritised striking Ukraine's energy infrastructure," it said.
In terms of what that means, the MoD said it suggested Russia was settling in for a longer-term campaign and is not aiming for a quick victory.
"Russian planners almost certainly recognise the growing importance of relative defence industrial capability as they prepare for a long war."
