Nato branded Russia the most "direct threat" to allied security after Moscow's invasion of Ukraine and vowed to modernise the beleaguered Ukrainian military, saying it stood four-square with Kyiv in "the heroic defence of their country."
Completing a summit dominated by the geopolitical upheaval caused by the invasion, Nato formally invited Sweden and Finland to join the alliance and pledged to reinforce combat-ready and rapid-reaction forces on its eastern flank, closest to Russia.
President Joe Biden announced additional US land, air and sea deployments across Europe, including a permanent army headquarters with accompanying battalion in Poland.
As the 30 national Nato leaders were meeting in Madrid, Russian forces intensified attacks in Ukraine, including missile strikes on the southern Mykolaiv region close to front lines.
The mayor of Mykolaiv city said a Russian missile had killed at least three people in a residential building there, while Moscow said its forces had hit what it called a training base for foreign mercenaries in the region.
Eight missiles struck Mykolaiv, a Ukrainian river port just off the Black Sea, its mayorsaid, including a hit on an apartment building, that killed four people and wounded five. The strikes came days after Ukraine said Russian missiles killed at least 18 people at a mall in the central town of Kremenchuk.
"There is fighting everywhere," said the governor of the eastern Luhansk region, much of which is now in Russian hands. The Russians are taking the city of Lysychansk building by building, he said, as they did before in nearby Sievierodonetsk.
Russian news agencies say Russian and Russian-backed separatist forces have blocked supplies along the Artyomovsk-Lysychansk highway.
Russia-installed officials said their security forces detained Kherson city mayor Kolykhayev after he refused to follow Moscow's orders. The officials have begun preparations for a referendum on the region joining Russia.
Reuters could not independently verify any of the battlefield accounts.
Nato invited Sweden and Finland to join the military alliance in one of the biggest shifts in European security in decades after Turkey lifted its veto.
The United States will create a new permanent army headquarters in Poland and deploy additional land, air and sea forces across the length and breadth of Europe in response to threats from Russia, US president Joe Biden said.
Ukraine's Foreign Minister Dmytro Kuleba praised Nato's "clear-eyed stance" on Russia and called for an "equally strong and active position on Ukraine" to bolster European security.
Russia views the plans by Sweden and Finland to join Nato as a destabilising move that will not improve its member states' security, Deputy Foreign Minister Sergei Ryabkov was quoted as saying.
The United States added five companies in China to a trade blacklist for allegedly supporting Russia's military and defence industrial base.
