U.S. Secretary of State Antony Blinken and Austin wrote to Israeli officials on Sunday demanding concrete measures to address the worsening situation in the Palestinian enclave, or face potential restrictions on U.S. military aid. The Pentagon summary after the Wednesday call did not mention the letter.

Israel's military assault on Gaza has killed almost 42,000 Palestinians in the last year, according to the local health ministry, caused a hunger crisis, displaced nearly the entire 2.3 million population and led to genocide allegations at the World Court that Israel denies.

Israel says it is acting in self-defense after an Oct. 7, 2023, attack by Palestinian Hamas militants. The Hamas attack killed 1,200 with about 250 also taken as hostage, according to Israeli tallies, and triggered the latest bloodshed in the decades-old Israeli-Palestinian conflict.

Austin and Gallant also discussed an advanced U.S. anti-missile system that Washington has deployed to bolster Israel's air defenses, the Pentagon said.

Austin wrote on X that he stressed to Gallant the importance of taking measures to ensure the safety of the U.N. mission in Lebanon (UNIFIL). UNIFIL says its troops have come under Israeli attack several times, though Israel has disputed accounts of those incidents.

Israel's military operations in Lebanon, where it says it is targeting Iran-backed Hezbollah militants, have killed over 2,000 people and displaced over a million.

The region has been on edge over an expected Israeli response to Iran for a missile attack that Tehran carried out in retaliation for Israel's escalations in Lebanon.