The United States of America (USA) has allowed Ukraine to use American weapons to attack targets in Russia, but only near the border with the area around the Ukrainian city of Kharkiv, Reuters reported, citing an unnamed American official.
A Russian offensive is underway in the Kharkiv region.
"The president recently directed his team to ensure that Ukraine can use US counter-attack weapons in the Kharkiv region to retaliate against Russian forces that are attacking them or are about to attack them," the official said.
The decision represents a change in the position of President Joseph Biden, who has so far refused to allow Kiev to use American weapons for attacks on Russian territory.
The American decision was preceded by increasingly frequent calls to leading NATO members to allow Kiev to use Western weapons to target targets inside Russia.
In the shadow of that debate is the two-day meeting of NATO foreign ministers in Prague, which began on Thursday and should be focused on the aid package for Ukraine.
Ukraine has been pressuring its supporters - most notably the US - to allow it to use long-range weapons to strike targets in Russia.
Some countries, including Great Britain and the Netherlands, say Kiev has the right to use their weapons to attack military targets in Russia.
This was supported by the Norwegian Minister of Foreign Affairs, Espen Bart Eide, who told NRK television that Kyiv should not fight "with one hand tied".
However, America and Germany have so far refused to allow Kiev to shoot targets across the border for fear that it could draw them into direct conflict with Moscow.
Ahead of the NATO meeting, Secretary General Jens Stoltenberg has repeatedly said it's time for members to review those restrictions because they hinder Kiev's ability to defend itself.
French President Emmanuel Macron said on Tuesday that Ukraine should be allowed to "neutralize" bases from which Russia attacks Ukrainian territory.
However, German Chancellor Olaf Scholz said that Ukraine should act within the framework of international law. Berlin also did not send Kiev weapons that could hit Russia.
In Washington, the White House said earlier that it remained opposed to Ukraine using US weapons to attack Russian territory, although Secretary of State Anthony Blinken hinted on Wednesday that that strategy could change.
Russian President Vladimir Putin warned of "serious consequences" if Western countries give the green light to Ukraine.
"NATO members, the US and European capitals have entered a new round of escalation of tensions in recent days and weeks," Kremlin spokesman Dmitry Peskov said on Thursday.
Those pushing for the lifting of restrictions on the use of Western weapons hope there is momentum for a change of attitude in Washington and other capitals, as Kiev struggles to stop a Russian offensive in the Kharkiv region.
The ministers in Prague should also determine a support package for Ukraine that would satisfy Kyiv, while at the same time potential membership would still not be likely in the near future.
Ukraine was told it should not expect concrete progress towards membership at a summit in Washington. Stoltenberg instead wants member states to commit to multi-year aid to Ukraine in the future.
Stoltenberg will ask the members to commit to a minimum of 40 billion euros per year in financial military aid for Ukraine, Reuters reported, citing a source from the alliance.
"We need to maintain that current level of support as a minimum so that Ukraine can count on it, for as long as necessary," the source said, adding that the allies were providing about 40 billion euros a year from a full Russian invasion of Ukraine in 2022.
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