Alliance head Jens Stoltenberg says Nato is stepping up chemical and nuclear defences for its forces in eastern Europe in the face of fears over Russia's war on Ukraine.
Ukrainian President Volodymyr Zelensky urges Nato members to provide Kyiv with offensive weapons, including tanks and fighter jets, one month into Russia's invasion.
The Group of Seven most industrialised nations says it will do everything in its power to hold Putin and his supporters personally responsible for the Ukraine invasion.
Kyiv,
Here are the latest developments in the war in Ukraine:
US President Joe Biden says that Russia's President Vladimir Putin has failed to divide the West with his war on Ukraine.
"Nato has never, never been more united than it is today. Putin is getting exactly the opposite of what he intended to have as a consequence of going into Ukraine," he says after a Nato summit in Brussels.
He also says Nato will "respond" if Russia uses chemical weapons in Ukraine, saying "the nature of the response would depend on the nature of the use".
Biden backs excluding Russia from the Group of 20 major economies over its invasion of Ukraine.
"I raised the possibility if that can't be done, if Indonesia and others do not agree, then we should in my view ask to have... Ukraine... attend the meetings as well," he says after a Nato summit in Brussels.
Nuclear defences
Alliance head Jens Stoltenberg says Nato is stepping up chemical and nuclear defences for its forces in eastern Europe in the face of fears over Russia's war on Ukraine.
Ukrainian President Volodymyr Zelensky urges Nato members to provide Kyiv with offensive weapons, including tanks and fighter jets, one month into Russia's invasion.
Addressing Nato's summit by video link, he says the alliance can prevent Ukrainian deaths "by giving us all the weapons we need".
Currently, Nato members are only supplying Kyiv with defensive equipment.
Biden will visit a town in Poland that is near the border with Ukraine on Friday, the White House says, as he seeks to show Western resolve against Russia's invasion.
He will be greeted by Polish President Andrzej Duda in Rzeszow, about 80 kilometres (50 miles) from the Ukrainian border.
The Group of Seven most industrialised nations says it will do everything in its power to hold Putin and his supporters personally responsible for the Ukraine invasion.
Meeting in Brussels, it stresses it has no quarrel with the Russian people.
The leaders say they will take action to block sanctions-hit Russian individuals and entities from evading penalties, and warn that they could impose more severe embargoes.
Zelensky says there is a "real" threat that Moscow will use chemical weapons in Ukraine, accusing Russia of having already used phosphorus bombs against civilians in the country.
Phosphorus bombs
The governor of the Lugansk region says phosphorus bombs were used in one village hit in overnight strikes on eastern Ukraine that killed at least four people, including two children.
Britain's ITV network broadcasts footage of phosphorus bombs dropping overnight on the flashpoint town of Irpin near Kyiv.
The G7 and the European Union pledge to block transactions involving the Russian central bank's gold reserves to hamper any bid by Moscow to circumvent Western sanctions.
Washington also unveils fresh sanctions on Russian lawmakers and defence contractors, while Britain slaps sanctions on 59 more Russian individuals and entities, including the mercenary group Wagner.
The UN General Assembly demands an "immediate" stop to Russia's war in Ukraine, in a non-binding resolution.
In a vote at UN headquarters in New York, 140 countries vote in favour, 38 abstain and five vote against the measure.
Russia accuses Nato member Poland, which neighbours Ukraine, of embarking on a "dangerous escalation" in tensions between Moscow and the West after Warsaw expelled 45 Russian diplomats for alleged espionage.
Russia's foreign ministry says Poland's actions are guided by "Russophobia" which it claims Nato has "elevated to the rank of official policy".
Chechen leader Ramzan Kadyrov says forces from his Russian region have taken control of the city hall in Ukraine's besieged southeastern port of Mariupol and hoisted the Russian flag.
There has been no independent confirmation of the Chechen claim.
The International Atomic Energy Agency expresses "concern" after Ukraine warns of bombardment by Russia of the town where staff working at the Chernobyl nuclear site live.
The Kremlin says Russian Defence Minister Sergei Shoigu is too busy for public appearances, as his absence from view for nearly two weeks prompts questions from journalists.
Shoigu, a close ally of President Vladimir Putin, reportedly last appeared in public on March 11 despite his leading role in Russia's military operation in Ukraine.