The Baltic state's Defence Minister Hanno Pevkur made the appeal following talks in Tallinn with visiting US counterpart Lloyd Austin.

"Whilst the United States is the biggest contributor in absolute terms, Estonia is in relative terms," Pevkur told reporters.

"Estonia's military assistance to Ukraine recently exceeded one percent of our GDP. Still we can and must do more."

He went on to list three ways in which the global community could further help Kyiv fight back against Russia's invasion, which began nearly a year ago.

Pevkur urged European and NATO allies to up their defence spending to over two percent of GDP, as "more can only be given when there is more to give".

Estonia itself has said it plans to exceed the three-percent mark next year.

Pevkur also called on the international coalition to reach at least 100 billion euros in combined military aid to Ukraine by the end of the year.

"We can talk about how substance also matters but trust me, there is at least 100 billion worth of things Ukraine needs already at this moment," he said.

To date, the United States and other countries have already contributed nearly half of that in security assistance to Ukraine.

Aid for Ukraine has covered almost all types of military equipment, from uniforms, small arms and ammunition to artillery rocket systems, air defences and armoured vehicles.

Finally, Pevkur called on the European Union to "urgently" support the Ukrainian defence with one million artillery rounds.

In recent days, there have been worries that Ukraine was fast depleting the stockpiles of artillery shells from the US and other allies.