(Reuters) - Russian President Vladimir Putin met his commanders in two regions of Ukraine that Moscow claims to have annexed, while Russian forces stepped up artillery bombardments and air strikes on the devastated eastern Ukrainian city of Bakhmut.
POLITICS/DIPLOMACY
* The U.S. and its NATO allies must remain alert for signs Putin could use a tactical nuclear weapon in a "managed" escalation of his war in Ukraine, the second-highest U.S. diplomat said.* Brazilian President Luiz Inacio Lula da Silva condemned the violation of Ukraine's territorial integrity by Russia and again called for mediation to end the war, a peace initiative that was criticized by the Ukrainian government.* South Korea might extend its support for Ukraine beyond humanitarian and economic aid if it comes under a large-scale civilian attack, President Yoon Suk Yeol said, signalling a shift in his stance against arming Ukraine for the first time.
* Ukrainian President Volodymyr Zelenskiy visited troops in the small eastern city of Avdiivka on Tuesday, thanked them for their service and was briefed by commanders on the battlefield situation, his office said.
* Russia's Foreign Ministry summoned the U.S., British and Canadian ambassadors for a dressing down after they condemned the conviction of an opposition politician on treason charges.
FIGHTING
* Russian drones struck Ukraine's southern Odesa region overnight and caused a fire at an infrastructure facility, the head of the military command of the Odesa region, said on Wednesday.
* Russian forces are stepping up their use of heavy artillery and air strikes in the devastated eastern Ukrainian city of Bakhmut, the commander of Kyiv's ground forces said on Tuesday. Russia is suffering significant losses in the battle, he said.
* A Russian artillery attack killed one person and injured nine more in the city of Kherson in southern Ukraine on Tuesday, regional officials said. Officials said a market in the city centre had been hit.
US REPORTER
* A Moscow court on Tuesday rejected an appeal from U.S. journalist Evan Gershkovich to be freed from pre-trial detention, meaning he will stay in a former KGB prison until at least May 29 while a spying case against him is investigated.
Gershkovich, a reporter for the Wall Street Journal, denies the espionage charges.
ECONOMY
* It will be very difficult for Europe to refill its gas storage to last year's levels after the continent ended the winter heating season with relatively low stockpiles, Russian natural gas giant Gazprom (MCX:GAZP) said on Tuesday.
* Poland agreed on Tuesday to lift a ban on the transit of Ukrainian grain and food products, but Ukraine said a wartime deal allowing it to safely ship grain from Black Sea ports remains under threat.
Russian Foreign Minister Sergei Lavrov will discuss the Ukraine Black Sea grain export deal with U.N. Secretary-General Antonio Guterres in New York next week, just weeks before the pact could expire unless Russian demands regarding its own exports are met.