The United States on Thursday gathered its allies in Germany for a new round of talks on bolstering Kyiv militarily, as Ukraine reported "good news" in recapturing several sites in the east.

US Defence Secretary Lloyd Austin will host the talks at the US airbase in Ramstein, aimed at underlining the "unity and solidarity" of allies in their backing for Ukraine.

NATO secretary general Jens Stoltenberg will be among the attendees, who include ministers and military chiefs from more than 40 countries.

The fifth round of talks under the "Ukraine Defence Contact Group" format came as President Volodymyr Zelensky said his forces had recaptured several settlements in the northeastern Kharkiv region from the Russians.

Ukraine has also been waging a counter-offensive in the south of the country since last week, where it has claimed to have recaptured several villages.

Kyiv has repeatedly urged allies for more heavy weapons as it pursues its push-back. Prime Minister Denys Shmygal reiterated the request when he visited Germany on Sunday.

Among the issues to be raised at Ramstein are the challenges of producing and restocking arms, as "there is a significant consumption of munitions in the conduct of this war that's occurring in Ukraine", said top US General Mark Milley.

The aim would be to look at what stocks are available in which countries and what would need to be sourced from industry, he said.

Artillery is proving decisive in the war and projectiles of all sorts are in huge demand.

With Ukraine and Russia fighting a war of attrition of munitions, stocks are similarly a crucial factor.

Having already exhausted all its Russian-made armaments, Ukraine is now entirely dependent on Western military support.

Russia, under heavy sanctions, is meanwhile turning to North Korea for huge quantities of rocket and artillery shells, said Washington.

- 'More effective' -

The United States has been Ukraine's biggest armaments supplier. It has already pledged $13.5 billion worth of various weapons, including anti-tank Javelin missiles and shells compatible with NATO's artillery systems.

Washington has also provided more advanced HIMAR multiple rocket launch systems, with precision-guided GMLRS rockets that can reach targets up to 80 kilometres (50 miles) away.

But Kyiv is seeking ATACMS -- precision-guided, medium range tactical missile which can be launched by the HIMAR systems and which are capable of striking at 300km.

The United States has so far refused, as it fears the missiles could land in Russian territory, sparking an even bigger conflict.

"Right now, the policy of the United States government is that we're not sending ATACMS," said Milley.

"We've had this conversation several times with my counterpart and others in the Ukrainian government."

Rather, he noted that the HIMARS and GMLERS have "proven to be very, very effective systems... against Russian forces".

"So we think that the range of the HIMARS is sufficient to meet the needs of the Ukrainians as they are currently fighting," he added.

US command spokesman Dave Butler also assessed that while Russia was firing its artillery at a higher rate than Ukraine, Kyiv's "are more effective".