Israel-Gaza updates: IDF says officer and soldier injured in attack from Lebanon

U.S. Secretary of State Antony Blinken and other officials have held back from publicly speculating whether the assassination of Hamas political leader Ismail Haniyeh will derail cease-fire negotiations, but several U.S. officials familiar with the talks say it certainly isn't good for the prospects of a deal.

The two assassinations of Hamas and Hezbollah leaders in the last 24 hours could have a chilling effect on the mediators, and what appears to be a recommitment to wartime mentality from both Israel and Hamas.

Blinken and others have recently said that an agreement is close, but always with the important caveat that the final gaps are the hardest to bridge.

Israel has also hardened some of its positions in recent weeks and the U.S. has never had full confidence in Hamas leader Yahya Sinwar’s desire to achieve a cease-fire or its insight into his thinking, officials say.

At the State Department briefing Wednesday, its deputy spokesperson, Vedant Patel, declined to speculate whether the assassinations would impact the talks and asserted that the department did not anticipate even a temporary pause in negotiations at this point.

-ABC News' Shannon K. Kingston

Hezbollah has confirmed that military commander Fouad Shukr, also known as Hajj Mohsen, was killed in an Israeli strike on a building in Beirut, calling it a "heinous attack and the major crime."

Hezbollah Secretary General Hassan Nasrallah will speak about the attack at a funeral procession on Thursday, according to Hezbollah.

In his first public statements since Israel killed top Hamas and Hezbollah leaders, Israeli Prime Minister Benjamin Netanyahu warned it would retaliate strongly "against any aggression."

"Challenging days are ahead of us. Since the attack in the Beirut, threats have been heard from all sides. We are ready for any scenario and will stand united and determined against any threat. Israel will charge a price, a very heavy price, for any aggression against us from any arena," Netanyahu said Wednesday.

Senior Hamas official Khalil al-Hayya said Tuesday that the talks with Israel are "meaningless" and that they were "close" to a deal but that Israeli Prime Minister Benjamin Netanyahu doesn’t want one.

"The negotiation is meaningless despite the bloodshed. We had a paper [agreement] and the deal was close. They do not want to stop being usurper. Netanyahu does not want a deal. Hence, we had dedicated all we could. Our path is not the path of surrendering," al-Hayya said during a press conference Wednesday.

Egypt also warned that the Israeli assassinations undermine truce talks and warned against dangerous security consequences.

Egypt condemned the killing of Hamas chief Ismail Haniyeh in Tehran and Hezbollah military leader Fouad Shukr in Beirut as a "dangerous escalation" by Israel that could fuel conflict in the region, according to a statement issued Wednesday.

The Egyptian foreign ministry said the assassinations "undermine the strenuous efforts made by Egypt and its partners to stop the war in the Gaza Strip" and "indicate the absence of Israeli political will to calm the situation."

-ABC News' Hami Hamedi and Ayat Al-Tawy