The United States will spend $3.5 billion to buy and donate 500 million doses of the Pfizer COVID-19 vaccine to some of the world’s poorest countries.
It has urged other G7 nations to follow suit.
The vaccine donation - the largest ever by a single country - was announced before US President Joe Biden meets leaders of the Group of Seven advanced economies in western England.
A senior Biden administration official said the US is not seeking favours in exchange for these doses and is not imposing conditions - political or economic or otherwise on countries for receiving these doses.
The 500 million doses are destined for the world's 100 poorest countries. A senior Biden administration official described the gesture as a "major step forward that will supercharge the global effort" with the aim of "bringing hope to every corner of the world."
"We really want to underscore that this is fundamentally about a singular objective of saving lives," the official said.
US drugmaker Pfizer and its German partner BioNTech have agreed to supply the United States with the vaccines, delivering 200 million doses in 2021 and 300 million doses in the first half of 2022.
The shots, which will be produced at Pfizer's US sites, will be supplied at a not-for-profit price.
U.S. National Guard troops patrolling the streets of Washington D.C. as part of what President Donald Trump said was his crackdown on crime will begin carrying weapons on Sunday night, two officials said.
Israeli strikes hit the Yemeni capital Sanaa on Sunday in retaliation for Houthi missiles fired towards Israel, with a Houthi health official saying the attack killed six people and wounded 86.
Syria's first parliamentary election under its new Islamist administration, scheduled for September, will not include the southern province of Sweida and two other provinces due to security concerns, the electoral commission said on Saturday.
Ukraine launched a drone attack on Russia on Sunday, forcing a sharp fall in the capacity of a reactor at one of Russia's biggest nuclear power plants and sparking a huge blaze at the major Ust-Luga fuel export terminal, Russian officials said.
Ukrainian President Volodymyr Zelenskyy marked Independence Day on Sunday alongside Canadian Prime Minister Mark Carney, who said Ukraine would receive more than C$1 billion ($723 million) in military aid from a previously announced package next month.
The UAE has sent another round of aid to the Gaza Strip, completing its 79th airdrop in cooperation with Jordan, in an effort to meet the urgent demands of the enclave's residents as they undergo dire humanitarian conditions.