US Secretary of State Antony Blinken warns the latest push for a Gaza ceasefire and hostage release deal is probably the best and possibly last opportunity, urging Israel and Hamas towards an elusive agreement.
However, with Palestinian Islamist group Hamas announcing a resumption of suicide bombing inside Israel after many years, and with Israeli air strikes still pounding Gaza, there is little sign of conciliation.
Hamas and another militant group, Islamic Jihad, said they were behind a blast near a synagogue in Tel Aviv on Sunday that killed the bomber and wounded one other person.
Suicide bombings "will return to the forefront" while the Gaza war continued, Hamas said in a statement.
The talks in Qatar last week paused without a breakthrough, but the negotiations are to resume this week based on a US "bridging proposal".
Blinken met Israeli President Isaac Herzog and Prime Minister Benjamin Netanyahu on Monday.
"This is a decisive moment, probably the best, maybe the last opportunity to get the hostages home, to get a ceasefire and to put everyone on a better path to enduring peace and security," Blinken told reporters before meeting Herzog.
Months of on-off talks have circled the same issues, with Israel saying the war can only end with the destruction of Hamas as a military and political force and Hamas saying it will only accept a permanent, and not a temporary, ceasefire.
There are disagreements over Israel's continued military presence inside Gaza, particularly along the border with Egypt, over the free movement of Palestinians inside the territory, and over the identity and number of prisoners to be freed in a swap.
Despite US expressions of optimism, both Israel and Hamas have signalled a deal will be difficult.
Hamas accused Netanyahu on Sunday of "thwarting the mediators efforts" and Turkey said Hamas envoys had told it US officials were "painting an overly optimistic picture".
Netanyahu told Israel's cabinet on Sunday that "we are conducting negotiations and not a scenario in which we just give and give", his office said.
However, a US official, asked if Hamas's comments amounted to a rejection of the deal, said Washington believed the bridging proposal it outlined last week addressed various concerns and would iron out difficult implementation aspects.
The current war in Gaza began on October 7 last year when Hamas gunmen stormed across the border into Israeli communities, killing about 1200 people and abducting about 250 hostages according to Israeli tallies.
Israel's military campaign has since levelled swathes of Gaza, driving nearly all of its 2.3 million people from their homes, giving rise to deadly hunger and disease and killing at least 40,000 people according to Palestinian health authorities.
The main UN agency in Gaza, UNRWA, said on Monday that 207 of its staff had been killed since the war began.
"They were engineers, teachers, medical staff. They were humanitarian workers," UNRWA said in a statement.
Blinken's visit comes as US President Joe Biden faces mounting pressure over his stance on the conflict, with his Democratic party holding its national convention on Monday amid worries about Muslim and Arab-American votes in swing states.
The conflict has put the entire Middle East region on edge, triggering months of border clashes between Israel and Lebanon's Iran-backed Hezbollah movement, and threatening a wider escalation drawing in major powers.
Blinken warned against "any steps that could derail this process, and so we're working to make sure that there is no escalation, that there are no provocations".
Israel's military said there had been more Hezbollah drone strikes on the country's north near the frontier with Lebanon on Monday.
In the latest Gaza fighting, Israeli military advances north of Khan Younis on Monday reached the coastal road, effectively cutting access between the city and areas to the north, residents said.
Israel also stepped up its bombardment of Gaza City suburbs overnight, and air strikes in Nuseirat camp and in Khan Younis in southern and central Gaza Strip medics said eight Palestinians were killed.
