Military exercises would take place with the consent of the guarantor countries.
More than a month into the biggest attack on a European nation since World War Two, more than 3.9 million people have fled abroad, thousands have been killed and injured, and Russia's economy has been pummelled by sanctions. In Mariupol, besieged by Russian forces, nearly 5,000 people have been killed, according to figures from the mayor which cannot be verified.
In parts now held by Russian troops, the few visible residents appeared ghostlike among charred and bombed apartment blocks. One little girl in a pink puffy coat and yellow knitted hat was playing with a stick in the ruins as explosions crackled in the distance. Two youths scavenged through rubble with a wheelbarrow.