Ukrainian President Volodymyr Zelenskyy met US House of Representatives Speaker Nancy Pelosi in the capital Kyiv on Sunday, the presidency said.
Zelenskyy thanked Pelosi for her visit, which was not announced in advance. "I am grateful to you for this signal of strong support from the United States," he said in a statement.
He also awarded the Order of Princess Olga to Pelosi for her "significant personal contribution" to strengthen US-Ukraine cooperation and supporting "sovereign, independent and democratic" Ukraine.
Pelosi confirmed the trip, saying that the congressional delegation travelled to Kyiv "to send an unmistakable and resounding message to the entire world: America stands firmly with Ukraine."
The speaker said additional US support is on the way as she hoped to pass a $33 billion aid package for Ukraine requested by President Joe Biden.
The delegation will also travel to Poland, which has taken in the most number of Ukrainian refugees, to thank its leadership "for their dedication and humanitarian efforts."
Russia launched what it calls a "special military operation" against Ukraine on February 24.
The war has killed thousands and driven more than 10 million Ukrainians from their homes, including over 5 million to neighbouring countries.
Children across parts of the US Northeast will stay home on Monday as a powerful winter storm forced school closures and pushed offices and transit systems onto emergency schedules, with officials across the region warning of dangerous travel conditions.
One of Mexico's most notorious drug lords, Nemesio Oseguera, or "El Mencho", has been killed in a military raid on Sunday, sparking widespread retaliatory violence.
Pakistan said it launched strikes on targets in Afghanistan after blaming recent suicide bombings, including assaults during the holy month of Ramadan, on fighters it said were operating from its neighbour's territory.
One police officer was killed and 24 other people were injured after several explosive devices detonated at midnight in Lviv in western Ukraine, the National Police said on Sunday.
President Donald Trump said on Saturday he will raise a temporary tariff from 10 per cent to 15 per cent on US imports from all countries, the maximum level allowed under the law, after the US Supreme Court struck down his previous tariff programme.
The move came less than 24 hours after Trump announced a 10% across-the-board tariff on Friday after the court's decision. The ruling found the president had exceeded his authority when he imposed an array of higher rates under an economic emergency law.
The new levies are grounded in a separate but untested law, known as Section 122, that al