Kiev (Ukraine) - (AFP) - Russia Wednesday resumed its participation in the Ukraine grain export agreement after receiving "written guarantees" from Ukraine that the corridor used for its transportation would be demilitarized.

For its part, the United States has expressed "growing concern" about Russia's possible use of nuclear weapons in Ukraine, while Moscow has in recent months doubled its threats and reassurance efforts.

Turkish President Recep Tayyip Erdogan, whose country is considered a guarantor of this crucial agreement to secure global food supplies, confirmed the resumption of Ukrainian exports in the Black Sea , as of Wednesday noon, through this safe passage.

"Russia considers that the guarantees it has received so far seem sufficient and is resuming implementation of the agreement," the Russian Defense Ministry said via Telegram.

On Wednesday evening, Ukrainian President Volodymyr Zelensky welcomed the continuation of the grain export agreement across the Black Sea, "which is important for the whole world."

"Today we achieved an important diplomatic result for our country and for the whole world: the implementation of the (Ukrainian) grain export initiative will continue," Zelensky said in his daily speech, which is posted on social media.

Zelensky considered that Russia's demand for guarantees to resume its participation in the Ukrainian grain export agreement "shows the failure of its aggression" against his country.

On Wednesday, US State Department spokesman Ned Price called for a renewal of the agreement, saying this would enhance the ability to secure "stability in this market and, most importantly, downward pressure" on basic foodstuffs in the world.
On Wednesday, United Nations Secretary-General Antonio Guterres "warmly" welcomed Russia's return to commitment to the effects of the agreement, according to his spokesman Stephane Dujarric.

On Saturday, Moscow suspended its participation in the grain deal after a march attack on its fleet stationed in Sebastopol Bay in Crimea, which it annexed. The Russian army held Ukraine responsible for this operation with the help of "British experts" and confirmed that it was carried out from the sea lane designated for Ukrainian exports.

It appears that a series of phone calls in recent days between Russian and Turkish officials, particularly Tuesday between Erdogan and President Vladimir Putin, and the UN mediation, the other guarantor of the agreement, have persuaded Moscow to reconsider its position.

"Thanks to the participation of an international organization, as well as Turkey's cooperation, the necessary written guarantees have been obtained from Ukraine that the humanitarian corridor and specific Ukrainian ports for the export of agricultural products will not be used to carry out hostile actions against Russia," the Russian military said.

But Putin threatened, on Wednesday, that Russia would again withdraw from the agreement to export Ukrainian grain through the Black Sea, in the event that Kiev “violated the guarantees” requested by Moscow.

Meanwhile, fears are growing of a possible Russian nuclear strike in Ukraine, after the United States on Wednesday expressed "growing concern" about this possibility, according to White House National Security Council spokesman John Kirby.

Kirby's remarks came in the wake of an article published by the "New York Times" newspaper, which indicated that high-ranking Russian officers had recently discussed the timing and how to use a tactical nuclear weapon in Ukraine, referring to a bomb that is weaker than a nuclear bomb.

On Wednesday, Kremlin spokesman Dmitry Peskov considered it "irresponsible" for Western media to "deliberately exaggerate the issue of nuclear weapons."

The other threat came from the former Russian president, a senior official in the National Security Council, Dmitry Medvedev.

On Tuesday, former Russian President Dmitry Medvedev, deputy head of the National Security Council, again referred to nuclear weapons, warning Ukraine against seeking to recover all the territories occupied by Russia.

Medvedev said that Ukraine's goal of regaining all its Russian-occupied territories, including the Donbass region and Crimea, would be "a threat to the existence of our state."

On Wednesday, the Russian Foreign Ministry said the "top priority" was to avoid war between nuclear powers, which would have "catastrophic consequences".

Russia accuses Ukraine of preparing to use dirty bombs against Russian forces, but Kiev suspects that Russia may take the initiative to attribute the attack to Ukraine in an attempt to justify Moscow's subsequent resort to nuclear weapons after it recently suffered losses in eastern and southern Ukraine.

On the front, the Ukrainian General Staff reported Wednesday that battles were going on in the east and that 25 towns in the east, center and south were being bombed.

The governor of Donetsk region in the east, Pavlo Kirilenko, reported that four civilians were killed in the past 24 hours.

AFP correspondents reported great damage in the village of Belozerka on the Kherson front in the south, the regional capital where Russian forces are fortifying their positions in preparation for an upcoming Ukrainian attack.

In Belozerka, Russian forces are shelling from the southern end of the road, in the position where they have holed up since their withdrawal from that town in March.

"At first we only thought that the invasion was over. But now it seems normal. We are used to it," said Angelika Borisenko, 20, a resident of the town.

And on Monday, Russia launched a series of cruise missile strikes on Kiev and the Ukrainian civilian infrastructure, which led to water and electricity cuts, especially in Kiev.

And on Wednesday, the Ukrainian Electricity Company announced new rationing of electricity, while the mayor of the Ukrainian capital, Vitali Klitschko, promised to publish a thousand "heating points" for the population by winter.

Ukrainian President Volodymyr Zelensky said that the Russian strikes destroyed 40 percent of Ukraine's energy facilities, prompting the country to stop its exports to the European Union, where prices are skyrocketing.