Under Donald Trump's peace plan for Gaza, the yellow line - which Israel withdrew to earlier this month - is the first of three stages of Israeli military withdrawal. It leaves it in control of about 53% of the Gaza Strip.
One Israeli newspaper, Yedioth Ahronoth, referred to it as effectively the new border in Gaza.
It's a remark that will please the far-right coalition partners of Prime Minister Benjamin Netanyahu.
The fortifications and demarcations Israel is now building along this boundary are meant to clearly divide the territory, but they may also help to blur the differing hopes and expectations of Mr Netanyahu's allies in Washington and at home.
How long he can keep both sets of expectations in play depends largely on this next stage of negotiations.
The boundary marked by the yellow line is temporary, but further withdrawal of Israeli forces rests on resolving the difficult issues pinned to the second stage of Donald Trump's deal – including the transfer of power in Gaza and the process for disarming Hamas.
Washington is keen that nothing upset this next delicate stage of negotiations. US Vice-President JD Vance flew in on Tuesday to push Netanyahu to press on with peace talks. Trump's negotiators Steve Witkoff and Jared Kushner met with the Israeli PM on Monday.
Israeli newspapers have been reporting that Netanyahu is receiving a stern message from his American allies to show restraint and not to endanger the ceasefire.
When Israel complained that Hamas had violated the terms of the ceasefire on Sunday, killing two soldiers, the response advocated by Mr Netanyahu's far-right National Security Minister was a one-word demand: War.
Instead, Israel carried out an intense, but brief, wave of air strikes before reinstating the truce, ensuring it could emphasize that its troops had been attacked inside the yellow line – keen to show Washington that Israel had not broken the rules.
Netanyahu has said the war will not end until Hamas is dismantled – its disarmament, and the full demilitarisation of Gaza, are among the conditions he has set.
But Israeli commentators are lining up to say that real decisions over Israel's military action in Gaza are now being made in Washington.
The yellow line – and the daunting task facing negotiators in this second stage of the deal – are clues as to why Netanyahu's coalition partners have chosen to wait, rather than carry out a threat to bring down his government.
The dream for many extremist settlers – and ministers – is that the next stage of this process will prove impossible to resolve, and that the yellow line will indeed become the de facto border, opening the way to new settlements on Gazan land.
However, the vast majority of Israelis want an end to the war and for the remaining bodies of hostages, and Israel's serving soldiers, to come home.
Benjamin Netanyahu is known for his political maneuverability; he prefers to keep his options open as long as possible. This deal proceeds in stages, with built-in caveats.
Agreeing to this first stage meant withdrawing to positions that left Israel in control of more than half of Gaza, and agreeing to a ceasefire to facilitate the return of hostages.
From here, aligning his US and domestic allies' goals will become increasingly challenging.
Netanyahu has repeatedly underscored that violations of the deal by Hamas – including its failure to disarm – would allow Israel to return to war.
If this is achieved the easy way, so much the better, he told the Israeli public earlier this month. If not, it will be achieved the hard way.
Donald Trump has echoed this sentiment, but so far, Washington has shown tolerance for delays and violations in implementing the deal, leaving Netanyahu with far less political freedom than he might wish.
