Russia pressed on with its offensive in eastern Ukraine on Thursday after NATO branded Moscow the biggest "direct threat" to Western security and agreed to plans to modernise Kyiv's beleaguered armed forces.
Ukrainian authorities said they were trying to evacuate residents from the frontline eastern city of Lysychansk, the focus of Russia's attacks where about 15,000 people remained under relentless shelling.
"Fighting is going on all the time. The Russians are constantly on the offensive. There is no let-up," regional Governor Serhiy Gaidai told Ukrainian television.
"Absolutely everything is being shelled."
In the southern Kherson region, Ukrainian forces were fighting back with artillery strikes of their own, Oleskiy Arestovych, adviser to the Ukrainian president, said in a video posted online.
At a summit on Wednesday dominated by Russia's invasion of Ukraine and the geopolitical upheaval it has caused, NATO invited Sweden and Finland to join and pledged a seven-fold increase from 2023 in combat forces on high alert along its eastern flank.
In reaction, President Vladimir Putin said Russia would respond in kind if NATO set up infrastructure in Finland and Sweden after they join the US-led military alliance.
Putin was quoted by Russian news agencies as saying he could not rule out that tensions would emerge in Moscow's relations with Helsinki and Stockholm over their joining NATO.
US President Joe Biden announced more land, sea and air force deployments across Europe from Spain in the west to Romania and Poland bordering Ukraine.
These included a permanent army headquarters with an accompanying battalion in Poland - the first full-time US deployment on NATO's eastern fringes.
"President Putin's war against Ukraine has shattered peace in Europe and has created the biggest security crisis in Europe since the Second World War," NATO Secretary-General Jens Stoltenberg told a news conference.
"NATO has responded with strength and unity," he said.
Britain said it would provide another 1 billion pounds ($1.2 billion) of military support to Ukraine, including air defence systems, uncrewed aerial vehicles and new electronic warfare equipment.
As the 30 national NATO leaders were meeting in Madrid, Russian forces intensified attacks in Ukraine, including missile strikes and shelling on the southern Mykolaiv region close to front lines and the Black Sea.
President Volodymyr Zelenskiy once again told NATO that Ukrainian forces needed more weapons and money, and faster, to erode Russia's huge edge in artillery and missile firepower, and said Moscow's ambitions did not stop at Ukraine.
The Russian invasion that began on February 24 has destroyed cities, killed thousands and sent millions fleeing. Russia says it is pursuing a "special military operation" to rid Ukraine of dangerous nationalists. Ukraine and the West accuse Russia of an unprovoked, imperial-style land grab.
The top US intelligence official Avril Haines said on Wednesday the most likely near-term scenario is a grinding conflict in which Moscow makes only incremental gains, but no breakthrough on its goal of taking most of Ukraine.