Pentagon says it will old send older model of tank rather than building new ones to ship, with aim of getting them to Ukrainian forces by the fall

Arriving in Ukraine by train, Biden's Kyiv visit marks first time in modern history that a US leader has traveled so close to a battlefront not under the control of US military

US President promises Zelensky the US will support Ukraine 'for as long as it takes; air raid sirens ring out as two leaders walk to lay a wreath in memory of fallen soldiers

US president headed to Europe to mark 1-year since start of war; half of Kremlin's tanks believed destroyed or captured; Zelensky calls to bar Russia from next Olympics

While Kyiv officials see transfer of Leopard and Abram tanks as a major breakthrough, Kremlin says significance is 'exaggerated,' vows to make them 'burn just like any others'

Biden says vehicles, part of new $400 million aid package, will help Kyiv 'counter Russia's evolving tactics and strategy on the battlefield'

Wall Street Journal quotes officials saying delivery could be announced this week as part of agreement that will see Germany send Leopard 2s

Spymaster also meets with other Ukrainian officials, while US gears up to deliver $2.5 billion in aid, including first Stryker armored vehicles

President Volodymyr Zelensky says tank-busting vehicles included in assistance 'exactly what is needed' in the fight against Moscow's forces

Idea was floated by Washington in the past, and in October House Speaker Pelosi took it up with Ukrainian counterpart; December 11 phone call from Biden finalized sensitive trip