Nato Secretary-General Jens Stoltenberg has said Western countries need to "prepare for the long haul".
Speaking to reporters after meeting US President Joe Biden at the White House on Thursday, Stoltenberg said Nato must continue to support Ukraine in what was becoming a long and sustained conflict:
"We just have to be prepared for the long haul because what we see is that this war has become a war of attrition where the Ukrainians are paying a high price for defending their own country on the battlefield, but also where we see that Russia is taking high casualties.
"Our responsibility is to provide support to Ukraine. Most wars - and also most likely this war - will at some stage end at the negotiating table, but what we know is that what happens around the negotiating table is very closely linked to the situation on the ground, on the battlefield, so we need to help them, to support them, so they can achieve the best possible outcome of this conflict."