WRAPUP 10-U.S. pledges Ukraine embassy reopening and military aid amid Russian warning

(Adds Belgorod shelling, White House warning of more sanctions, Russian foreign minister comments)

* Russia has 'failed' in its war aims in Ukraine - Blinken

* Russia demands Washington stop sending arms to Kyiv

* Washington commits $713 million in military assistance

* Russia targets rail lines to disrupt arms supplies - Kyiv

By Pavel Polityuk and Natalia Zinets

KYIV, April 25 (Reuters) - The United States will reopen its Ukraine embassy, and President Joe Biden's top diplomat and most senior defense official promised more military aid while visiting Kyiv as Russia warned against arming its enemy and battles raged in the east.

U.S. Secretary of State Antony Blinken and Defense Secretary Lloyd Austin said their ability to come to Ukraine's capital was proof of its tenacity in forcing Moscow to abandon an assault on the capital city last month.

"In terms of Russia’s war aims, Russia has already failed and Ukraine has already succeeded," Blinken said after the visit.

Russian Foreign Minister Sergei Lavrov late on Monday said that the crisis will end with an agreement but its content will depend on the military situation, criticizing Kyiv for only imitating negotiations.

Earlier, Russia's ambassador in Washington told the United States to halt arms shipments, warning that large Western deliveries of weapons were inflaming the conflict.

The two-month-old war has killed or injured thousands, reduced towns and cities to rubble and forced over five million people to flee abroad as the biggest attack on a European state since 1945 drags on.

Russian forces were forced to pull back from the outskirts of Kyiv in the face of stiff resistance and have yet to capture any of the biggest cities.

The United States pledged $713 million in new assistance for Ukraine and other countries in the region seen as potentially vulnerable to Russian threats. The White House also warned that more sanctions against Russia were likely.

An extra $322 million in military aid for Ukraine would take the total U.S. security assistance since the invasion began to about $3.7 billion, one official said.

Russian President Vladimir Putin on Monday attacked the West, saying it had failed to divide Russian society and accused it of inciting Kyiv to plan attacks on Russian journalists, in comments dismissed by Ukraine's security service.

Russia was trying to disrupt arms supplies from Kyiv's allies by bombing its rail infrastructure, Ukraine's military command said.

Russia's defence ministry said later its missiles destroyed six facilities powering the railways that were used to deliver foreign weapons to Ukrainian forces in the eastern Donbas region.