Ukrainian President Volodymyr Zelensky has underscored the urgency of helping his country’s military improve its position against Russia in a video meeting with leading economic powers, who in turn pledged to support Ukraine “for as long as it takes”.

Mr Zelensky addressed the delicacy of the moment for Ukraine in its war with Russia to the G7 summit as the leaders of the major economies prepared to unveil plans to pursue a price cap on Russian oil, raise tariffs on Russian goods and impose other new sanctions.

The US is also preparing to announce the purchase of an advanced surface-to-air missile system for Kyiv to help Ukraine fight back against Vladimir Putin’s aggression, a day after Russian missiles hit the Ukrainian capital of Kyiv for the first time in weeks and as its military continued a full-on assault on the last remaining Ukrainian hold-out in the Luhansk region.

The new aid and efforts by the G7 to punish Moscow come as Mr Zelensky has openly worried that the West has become fatigued by the cost of a war that is contributing to soaring energy costs and price hikes on essential goods around the globe.

The Ukrainian leader discussed his strategy for the course of the war, which has transformed into a bloody artillery battle in the country’s west and east.

US national security adviser Jake Sullivan said Mr Zelensky’s top request was for further air defence systems, followed by economic support to help his government meet its financial obligations.

Mr Sullivan said most of the conversation was “about the way forward and how President Zelensky sees the course of the war”.

Mr Zelensky also briefed the G7 leaders on how his administration is using the assistance he has received to date “to maximise Ukraine’s capacity both to resist Russian advances, and to pursue counter attacks where possible”, Mr Sullivan said.

The Ukrainian president also told the leaders that he needs to be in stronger position before engaging in peace talks with Russia, according to a senior French diplomat.

After hearing from Mr Zelensky, the leaders pledged in a statement to support Ukraine “for as long as it takes”. They said it is up to Ukraine to decide on a future peace settlement.

President Joe Biden is expected to soon announce the US is purchasing NASAMS, a Norwegian-developed anti-aircraft system, to provide medium to long-range defence for Ukraine, according to a source.

NASAMS is the same system used by the US to protect the sensitive air space around the White House and US Capitol in Washington.

Additional aid includes more ammunition for Ukrainian artillery, as well as counter-battery radars, to support its efforts against the Russian assault in the Donbas, the source said.

Mr Biden is also announcing a 7.5 billion dollar (£6.1 billion) commitment to help Ukraine’s government meet its expenses, as part of a drawdown of the 40 billion dollar (£32 billion) military and economic aid package he signed last month.

German Chancellor Olaf Scholz, the summit’s host, said after meeting Canadian Prime Minister Justin Trudeau on Monday: “We are taking tough decisions… we will help… Ukraine as much as possible but that we also avoid that there will be a big conflict between Russia and Nato.”