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The US Defence Department denied on Thursday that it provided intelligence on the locations of Russian generals on the battlefield so that Ukrainian forces could kill them.
Reacting to an explosive New York Times report on US support for Ukraine's military, Pentagon spokesman John Kirby said it was true that the US supplied Kyiv's forces with military intelligence “to help Ukrainians defend their country”.
“We do not provide intelligence on the location of senior military leaders on the battlefield or participate in the targeting decisions of the Ukrainian military,” Mr Kirby said.
In a separate revelation, US media reported later on Thursday that the US had shared intelligence that helped Ukraine sink the Russian warship Moskva last month, in a huge blow to President Vladimir Putin.
Anonymous officials, in a story first published by NBC, said Ukraine asked Washington about a ship sailing in the Black Sea, whose location the US helped confirm in addition to identifying it as the Moskva.
However, the US did not know that Ukraine would target the flagship vessel, the officials said.
Ukraine has been particularly successful in attacking Russian command positions, and, according to reports, came close last week to striking a location near the front lines in the Donbas region where Russia's top general, Valery Gerasimov, was believed to be visiting troops.
Ukraine forces may have shelled the location just a few hours after Mr Gerasimov had left, the unconfirmed reports said.
Citing anonymous senior US officials, the New York Times' Wednesday report, which Mr Kirby refuted, said that of the approximately dozen Russian generals killed by Ukrainian forces, “many” had been targeted with the help of US intelligence.
The newspaper said the US had provided details on the Russian military's mobile headquarters, which frequently change location.
It reported that Ukrainian forces used that information in tandem with their own to conduct attacks on senior Russian officers.
Mr Kirby said Ukraine makes its own decisions on whether to target a Russian leader or not.
“Ukraine combines information that we and other partners provide with the intelligence that they themselves are gathering on the battlefield,” he said.
“Then they make their own decisions, and they take their own actions.”
The White House National Security Council slammed the New York Times report as “irresponsible”.
“The United States provides battlefield intelligence to help the Ukrainians defend their country,” NSC representative Adrienne Watson said.
“We do not provide intelligence with the intent to kill Russian generals.”
Washington is supplying billions of dollars of military equipment and munitions to Ukraine and is training its forces on how to operate them.
It is also providing Kyiv with information garnered from satellites, electronic surveillance operations and other sources of intelligence.
But the White House and Pentagon have sought to limit knowledge of the full extent of the US assistance, hoping to avoid provoking Russia into a broader conflict beyond Ukraine's borders.
Even so, Washington's support for Ukraine has only grown, and become more forthright, since Russia invaded on February 24.
At the beginning the US said it wanted only to help Ukraine survive.
But now Washington says its goal in the war is to debilitate Russia for the long term.
“We want to see Russia weakened to the degree that it can't do the kinds of things that it has done in invading Ukraine,” US Secretary of Defence Lloyd Austin said after a visit to Kyiv late last month.