in what you quoted, nothing says "U.S. officials believed..." as the headline states
> Killing senior Iranian leaders had been part of Israel’s strategy from the start of the war. But American concerns about the targeting of two particular Iranian officials — Abbas Araghchi, Iran’s foreign minister, and Mohammad Bagher Ghalibaf, the speaker of the Parliament — spiked during delicate cease-fire negotiations that began in April.
> Fearful that an Israeli assassination effort would doom the negotiations, the United States, according to some of the officials, went so far as to ask other countries in the region to warn Iran about the possibility Israel could target the two officials.