Russia is now using nuclear-capable missiles with non-explosive warheads to exhaust Ukraine's air defences, the Ukrainian military has said.
It displayed what it said were fragments of Soviet-made X-55 cruise missiles - designed for nuclear use - found in Ukraine's two western regions.
The rockets are being launched to "exhaust the air-defence system of our country," a Ukrainian official said.
He said tests on the fragments did not show abnormal levels of radioactivity.
Ukrainian military experts say Russia may have significantly depleted its vast missile arsenal after carrying out wave after wave of massive strikes on Ukraine's critical infrastructure in recent weeks.
Moscow is now resorting to using blunt projectiles that still cause devastation, they say. A UK intelligence report in November came to similar conclusions.
Russia - which launched a full-scale invasion of Ukraine on 24 February - has made no public comments on the issue.
At a briefing on Thursday in Ukraine's capital Kyiv, military official Mykola Danyliuk showed reporters what he described as fragments of X-55 cruise missiles (known as AS-15 by Nato) found in the Lviv and Khmelnytsky regions.
He said the projectiles were designed in Soviet times to hit "strategic targets with predetermined co-ordinates".
The UK said the missiles were designed "exclusively as a nuclear delivery system".
However, it is believed the Russian military removed the nuclear warheads from the missiles fired at Ukraine and replaced them with an inert system.
Mr Danyliuk stressed that even a missile armed with a non-explosive warhead "posed a significant danger" because of its kinetic energy and fuel residues.
"This is evidenced by the latest strike when a X-55 missile hit a residential building."
Testing indicated "no contact [of the missile] with nuclear elements", he added.
On Thursday, an air alert was briefly in place across all of Ukraine - with the exception of the Russian-annexed southern Crimea peninsula - after reports that Russian war planes may be preparing to carry out a fresh wave of missile strikes. The alert was later discontinued.
In other developments on Thursday:
- Moscow said a move by the German parliament on Wednesday to recognise the 1930s mass starvation of millions of Ukrainians as genocide was an attempt to "demonise" Russia
- Ukraine's nuclear operator sacked the acting chief engineer of the Russian-seized Zaporizhzhia nuclear power station, accusing him of treason and collaboration with the Kremlin