First Thing: Hamas issues threat over lives of hostages

Israeli troops reach heart of Khan Younis as Benjamin Netanyahu calls on Hamas fighters to surrender. Plus, the oldest black hole ever observed

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Good morning.

Israeli tanks have reached the heart of Gaza's southern city of Khan Younis, as Hamas issued fresh demands for Palestinian prisoners to be released while at the same time threatening the lives of the hostages they continue to hold.

Why is the US president under scrutiny over his support for Israel? The support of Joe Biden's administration for Israel's war in Gaza has come under intensified scrutiny after it revealed it had bypassed Congress to supply tank shells, and was reported not to be carrying out continual assessments of whether Israel was committing possible war crimes.

What will Zelenskiy do while in Washington? As well as meeting Biden, he has also been invited to address US senators on Tuesday morning in the Capitol, a Senate leadership aide said. A private meeting between Zelenskiy and the US House of Representatives speaker, Mike Johnson, will also be held in the Capitol on Tuesday, Johnson's spokesperson Raj Shah said in an email to Reuters.

What are opponents to US support for Ukraine up to? Allies of Hungary's far-right prime minister, Viktor Orban, will hold a closed-door meeting with Republicans in Washington to push for an end to US military support for Ukraine, the Guardian has learned. Members of the Hungarian Institute of International Affairs and staff from the Hungarian embassy in Washington will on Monday begin a two-day event hosted by the conservative Heritage Foundation thinktank, with some attenders, including Republican members of Congress, invited to join closed-door talks the next day.