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, and was careful to emphasise 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 the 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 the yellow line will indeed become the de facto border, opening the way to new settlements on Gazan land. Some hardliners would like Israel to annex the whole of the Gaza Strip.
The vast majority of Israelis want an end to the war and for the remaining bodies of the hostages, and Israel's serving soldiers, to come home.
But Israel's prime minister is known as a politician who likes to keep his options as open as possible, for as long as possible, and this is a deal in stages, with caveats built in.
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 in order to get hostages home.
From here, it will become harder to align the goals of his US and domestic allies.
Benjamin Netanyahu has repeatedly underlined 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 said the same. But Washington has so far shown a tolerance for delays and violations in implementing the deal on the ground, leaving Netanyahu with far less political room than perhaps he'd like.
