KYIV, Ukraine — The United States and Britain pledged nearly $1.5 billion in additional aid to Ukraine on Wednesday during a visit to Kyiv by their top diplomats as Ukrainian officials renewed their pleas to use Western-provided missiles against targets deeper inside Russia. Secretary of State Antony Blinken announced more than $700 million in humanitarian aid, while British Foreign Secretary David Lammy confirmed his country would provide another $782 million in assistance and loan guarantees. Much of the effort was aimed at bolstering the energy grid that Russia has repeatedly pounded ahead of an expected difficult winter. The latest American aid package includes $325 million in energy support to help repair and restore Ukraine’s power generation facilities, provide emergency backup power for critical services and strengthen the physical security of energy infrastructure. Some $290 million will fund food, water, shelter, health care and education programs for Ukrainians in need in the country and refugees outside the country. The remaining $102 million will be used for mine-removal work. Blinken and Lammy traveled together to the Ukrainian capital on a rare joint tour to underscore their commitment to the country in its war. Air-raid sirens sounded repeatedly during the visit, causing delays in their schedule and forcing them to cancel a wreath-laying ceremony. The diplomatic visit unfolded as Russia’s bigger and better-equipped army bears down on Ukraine’s eastern Donetsk region and conducts aerial attacks on cities across the country using missiles, glide bombs and drones that claim many civilian casualties. Lammy said the 2 1/2-year conflict is at a “critical” juncture following Ukraine’s daring incursion last month into Russia’s Kursk region. “We convey the deepest condolences for the shocking attacks that we have seen, over the loss of civilian life, particularly women and children — horrific, barbaric, unbelievable,” Lammy said. But relations between Ukraine and its Western partners have been increasingly strained by Kyiv’s repeated appeals for the West’s authorization to use long-range weapons from the United States and other allies to strike targets deeper inside Russia. That issue took on added urgency after Russia’s latest reported acquisition of ballistic missiles from Iran, but Western leaders have so far balked at Ukraine’s request, fearing that, if granted, it could escalate the war. President Biden has allowed Ukraine to fire U.S.-provided missiles across the border into Russia in self-defense, but has largely limited the distance they can be fired. Ukrainian President Volodymyr Zelenskyy said he hoped for changes to those limitations. He said he hoped to speak to Biden later this month, noting that U.S. military and financial support is crucial. “We rely heavily on it, and frankly, we can’t prevail without it,” Zelenskyy said. However, U.S. Defense Secretary Lloyd Austin last week pushed back on the idea that long-range strikes would be a game-changer. The Ukrainians have other means to strike long-range targets, he said. A hard winter likely lies ahead for Ukraine. Its power grid is under severe strain after Russian missiles and drones knocked out around 70% of the country’s generation capacity. Kyiv officials will also have to navigate the outcome of the U.S. election in November, which could produce important policy shifts in Washington. Former President Donald Trump said in a presidential debate Tuesday that he wants the war to end but did not clearly say he wants Ukraine to win. Ukrainian officials politely sidestepped making any comment on the debate. Zelenskyy said he did not watch it, while Ukraine’s foreign minister, Andrii Sybiha‎, insisted U.S. policy was ultimately unlikely to change. “Yes, it’s clear that there will be a new president. But we believe, and are convinced, in the strong support of the American people,” Sybiha said. “We are firmly, firmly convinced that this support will continue.”