The United States has been urging countries through its diplomatic engagements to tell Iran that escalation in the Middle East is not in their interest, State Department spokesperson Matthew Miller said on Monday.

Speaking at a daily briefing, Miller said this was a “critical moment” for the region and that US Secretary of State Antony Blinken was working the phones to help calm the tensions, but also said Washington was preparing for all possibilities.

Hamas leader Ismail Haniyeh was assassinated in the Iranian capital Tehran last week, an attack that drew threats of revenge on Israel and fueled further concern that the conflict in Gaza was turning into a wider Middle East war.

Iran has blamed Israel and said it will “punish” it; Israeli officials have not claimed responsibility for the killing. Iran backs Hamas, which is at war with Israel in Gaza, and also the Lebanese group Hezbollah, whose senior military commander Fuad Shukr was killed in an Israeli strike on Beirut last week.

The top US diplomat on Monday spoke with Qatari Prime Minister Sheikh Mohammed bin Abdulrahman Al Thani and Egyptian Foreign Minister Badr Abdelatty on the tensions in the Middle East.

“One of the points of the engagements that we have had is to urge countries to pass messages to Iran and urge countries to make clear to Iran that it is very much not in their interests to escalate this conflict, that it is very much not in their interest to launch another attack on Israel,” he said.

Miller did not say definitively whether or not Washington’s messages have been disseminated to Iran or through which channel.

“I would expect that some of them would pass that message along and impress that point upon the government of Iran,” he added.