US National Security Advisor Jake Sullivan expressed concerns on Saturday about potential Russian strikes targeting Ukrainian nuclear power plants.

Speaking at a forum in Kiev, Sullivan highlighted Russia's previous attacks on "civilian energy infrastructure," alleging that Moscow had also "targeted Ukraine's nuclear plants."

"I think we could see that again," he stated.

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Sullivan, who arrived in Kiev alongside the UK Defense Minister earlier this week, also addressed the delays in delivering aid to Ukraine, explaining that the issue stemmed from logistical challenges rather than a lack of political will.

He emphasized the importance of overcoming these difficulties to better support Ukraine in its fight against Russia.

"But given what Ukraine is up against, we've got to do more, and we've got to do better."

Additionally, the US State Secretary announced that US President Joe Biden and Ukrainian President Volodymyr Zelensky are expected to meet at the United Nations General Assembly at the end of September.

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Biden and British Prime Minister Keir Starmer met in Washington on Friday to discuss, among other issues, the possibility of allowing Kiev to use Western-provided long-range missiles to target Russian positions.

Both the US and the UK have already supplied Ukraine with ATACMS and Storm Shadow long-range missiles, respectively. But, so far, Washington claims it had not authorized Kiev to use US-provided weapons to strike deep inside Russian territory.

Speaking to reporters at the White House, Starmer confirmed that he had a "wide-ranging discussion about strategy" with Biden but clarified that the meeting "wasn't a meeting about a particular capability."

NATO at direct war with Russia

Russian President Vladimir Putin stated on Thursday that NATO nations are not only debating the possibility of Kiev using Western long-range weaponry but also contemplating whether to intervene actively in the Ukrainian war.

"In fact, only servicemen from NATO countries can make flight assignments to these missile systems. Ukrainian servicepeople cannot do that. So this is not a question of allowing the Ukrainian regime to attack Russia with these weapons or not. It is a question of deciding whether NATO countries are directly involved in a military conflict or not," Putin said.

"If this decision is taken, it will mean nothing else than direct participation of NATO countries - the USA and European countries - in the war in Ukraine," Putin stated. 

Echoing Putin's statement, Russian Ambassador to the United Nations Vassily Nebenzia warned on Friday that Moscow will consider NATO countries at "direct" war with Russia if restrictions on Ukraine using long-range weapons to target the country are lifted.

"In this case, we will have to take, as you understand, relevant decisions with all the consequences for this that the Western aggressors would incur," he added.