Further sanctions against Russia have not been ruled out but US Secretary of State John Kerry said he hoped the international community can find a way for Russia and Ukraine to work together to resolve the political tension.
He told reporters at a briefing in Sydney: "Our hope is that in the next days and weeks, we can find a way for (Ukrainian) President Poroshenko and Ukraine to be able to work with the Russians to provide the humanitarian assistance necessary in the east."
He added: "Our hope is that can happen through the diplomatic process, but we've all learned that we need to be cautious and strong at the same time and our responses clear about what is acceptable and what is not acceptable."
Kerry was speaking as Russia said a convoy of 280 trucks carrying humanitarian aid set off for Ukraine on Tuesday, amid warnings that could be an attempt by Moscow to install a permanent presence in the country.
More top news
Public sector organisations will have to publish information on any gender pay gap from Friday, in a bid to tackle discrimination.
Remarkably mild night for March
President Trump is cutting funding to cities that shelter illegal immigrants, but some are fighting back.