Ukraine has warned the conflict could spiral into World War Three if it loses to Russia as the US Congress debates a bill to provide billions in military aid.
The US House of Representatives will have its long-awaited vote on aid for Ukraine as soon as Saturday, Republican Speaker Mike Johnson said on Wednesday, amid fierce opposition on the right of his party.
Speaking to the BBC, Ukrainian prime minister Denys Shmyhal expressed “careful optimism" that the bill would pass, which earmarks $61bn (£49bn) for Kyiv.
He told the broadcaster: “We need this money yesterday, not tomorrow, not today."
"If we will not protect... Ukraine will fall," he added. "So the global, the global system of security will be destroyed... and all the world will need to find... a new system of security.
"Or, there will be many conflicts, many such kinds of wars, and in the end of the day, it could lead to the Third World War."
Volodymyr Zelensky has also previously said that the conflict could lead to World War Three if Russia won as it could next invade Poland, a Nato member.
The bill, which totals more than $95 billion in security assistance, also includes some $26.38 billion for Israel security measures and humanitarian measures, some of which will cover the cost of US military operations.
The security aid effort gained urgency following Iran's weekend attacks on Israel in retaliation for a suspected Israeli airstrike on Iran's embassy compound in Damascus on April 1.
Mr Johnson said he would give House members 72 hours until midday Saturday to review the bill and offer amendments before a vote on final passage.
He also said he would release a separate border security bill, meeting a demand from conservatives.
Democratic President Joe Biden called on Congress to pass the bills quickly.
“I will sign this into law immediately to send a message to the world: We stand with our friends, and we won’t let Iran or Russia succeed," Mr Biden said in a statement.
The Ukraine measure includes a provision that economic assistance to Kyiv - not military - should be repaid, which was a conservative demand.
However, the Biden administration could waive that requirement.
Democratic support for the bill is essential, given the slim Republican majority in the House and opposition from far-right Republicans.
