Ukrainian troops are holding out against attacks near two towns in the eastern Donbas region, President Volodymyr Zelenskiy reported on October 26, saying the front line has not significantly changed.
Zelenskiy said the fiercest battles were taking place near Avdiyivka and Bakhmut.
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"This is where the craziness of the Russian command is most evident. Day after day, for months, they are driving people to their deaths there, concentrating the highest level of artillery strikes," he said in his nightly address.
Russian forces have repeatedly tried to seize Bakhmut, which sits on a main road leading to the cities of Slovyansk and Kramatorsk. British intelligence has said Moscow may see the capture of Bakhmut as a prerequisite for advancing to the two cities -- the most significant Ukrainian-controlled parts of the Donetsk region.
Russian-installed authorities in Shakhtarsk, east of the city of Donetsk, said Ukrainian shelling had set ablaze fuel tanks at the town's railway station.
The reports could not be independently verified.
Zelenskiy did not provide an update on the situation in the Kherson region in southern Ukraine, which has been the scene of recent movements on both sides.
"Generally, we are strengthening our positions all over the front line, reducing the invaders' capabilities, destroying their logistics, and preparing good news for Ukraine," he said.
Russia, meanwhile, repeated the unfounded claim that Ukraine plans to set off a dirty bomb.
This time it was Russian President Vladimir Putin who made the accusation, speaking in remarks carried by Russian TV.
Putin said Ukraine plans to “use a so-called dirty bomb as a provocation.” It was the first time the Russian president made the unsubstantiated allegation, which his officials have been repeating since the weekend.
Putin made the remarks as he monitored drills of Russia’s strategic nuclear forces.
"Under the leadership of...Vladimir Putin, a training session was held with ground, sea, and air strategic deterrence forces during which practical launches of ballistic and cruise missiles took place," the Kremlin said in a statement.
Russian Defense Minister Sergei Shoigu reported to Putin that the exercise simulated a “massive nuclear strike” retaliating for a nuclear attack on Russia.
The United States said Russia provided advance notice of the annual drills, which are taking place as NATO carries out its own annual nuclear exercises.
NATO Secretary-General Jens Stoltenberg called Russia’s unsubstantiated statements about the use of a dirty bomb "absurd."
The NATO allies “reject this blatantly false accusation, and Russia must not use false pretexts to escalate the war further,” Stoltenberg told reporters at NATO headquarters in Brussels.
Ukraine and its Western allies have denied the claims and contend that Russia might itself try to detonate a dirty bomb, a weapons that would use the explosion of a conventional warhead to spread radioactive, biological, or chemical materials over an area.
Shoigu on October 26 called his counterparts from India and China to share Moscow’s concern about “possible Ukrainian provocations involving a dirty bomb,” according to the Russian Defense Ministry.
Kremlin spokesman Dmitry Peskov told reporters on October 26 that Russia would "vigorously" continue to make the case to the international community that it believed Ukraine intended to detonate a "dirty bomb" with radioactive contaminants.
U.S. Secretary of State Anthony Blinken said the United States has “communicated directly and very clearly to the Russians” the consequences of such an attack.
Blinken, speaking at an event sponsored by the U.S. news outlet Bloomberg, did not specify when the Russians were informed or who did it.
Blinken repeated that the United States is "very closely" following Russia’s comments about the use of nuclear weapons but "does not see any reason to change its nuclear position."
Russia's statement that Ukraine is considering the possibility of using a dirty bomb is "another fabrication and is the height of irresponsibility on the part of a nuclear state," Blinken said.
He noted that Russia has a history of accusing others of doing something they themselves have done or are about to do. He also said the United States was in direct communication with the Russians about their attempts to use the false claim as a pretext for any escalation.
Moscow over the weekend claimed Ukraine was preparing to use a so-called dirty bomb on its own territory, drawing immediate dismissal from the United States and other countries that have backed Ukraine.
Kyiv and its allies suspect Russia might have made the claim to set up a "false flag" attack in which it would use a dirty bomb itself but would blame the attack on Ukraine and use it to justify the use of conventional nuclear weapons by Moscow.
"Let me just say Russia would be making an incredibly serious mistake were it to use a tactical nuclear weapon." U.S. President Joe Biden told reporters on October 25 . "I cannot guarantee you that it is a false flag operation yet. We don’t know. But it would be a serious mistake."
Shoigu presented no evidence for the claim when he spoke on October 23 with his counterparts from several NATO countries, including Britain, France, and the United States, who dismissed the claim after the series of calls.
WATCH: Speaking to Current Time in Riga on October 22, Latvian Defense Minister Artis Pabriks said Russian President Vladimir Putin cannot change the course of war in Ukraine by dropping nuclear bombs.
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'Russia Has...Lost': Latvian Defense Minister Says Ukraine War Exposes Who Is Who In Europe
Moscow took its accusations against Ukraine to the UN Security Council on October 25, and the country's UN ambassador, Dmitry Polyanskiy, said afterward that Russia was "satisfied because we raised the awareness."
Speaking to reporters, he added: "I don't mind people saying that Russia is crying wolf if this doesn't happen because this is a terrible, terrible disaster that threatens potentially the whole of the Earth."
The International Atomic Energy Agency (IAEA) said earlier on October 25 that it was preparing to send inspectors to two Ukrainian sites in the coming days in reaction to Ukraine's request for an inspection following Russia's claims.
Enerhoatom, Ukraine’s nuclear energy operator, issued a statement on October 24 voicing its concern that Russia’s statements “may indicate that Russia is preparing an act of nuclear terrorism.”
Russian troops have occupied Ukraine’s Zaporizhzhya nuclear power plant, Europe's largest, since March. It is still run by Ukrainian engineers though Russia claimed after its illegal annexation of the Zaporizhzhya region that it is on Russian territory.
Enerhoatom said that Russian forces have carried out unauthorized, secret construction work over the last week at the plant in the area of the spent nuclear fuel storage facility.
Russian officers controlling the area won’t give access to Ukrainian staff or monitors from the IAEA that would allow them to see what they are doing, the operator said.
Enerhoatom added that it “assumes” the Russians “are preparing a terrorist act using nuclear materials and radioactive waste stored” at the plant.