Kerry did not elaborate, and it was the same type of optimistic language he has used since persuading Israel and the Palestinians to resume talks, their first substantive negotiations in five years, last July. Under heavy American pressure, the sides set an April target date for resolving their decades-long conflict. While negotiators have quietly been meeting, neither side has shown optimism. Instead, the talks have been repeatedly marred by mistrust and finger-pointing.
The Palestinians have accused Israel of negotiating in bad faith, pointing to continued Jewish settlement construction in east Jerusalem and the West Bank, lands captured by Israel in 1967 and sought by the Palestinians for their state. With roughly 550,000 Jews now living in these territories, the Palestinians say the chances of being able to divide the territory between the two peoples are running out.
Plans to build more settlement homes have sparked a series of crises in the talks. Kerry has said the construction raised questions about Israel's commitment to peace, and the Palestinians have threatened to withdraw from the talks in protest.
Mohammed Ishtayeh, a former negotiator, said he resigned last month after concluding that the gaps would never be bridged.
"I found no partner in Israel in the talks and the Israelis are not serious. They came to talk just to avoid the international pressure and isolation," he said. "All Israel wanted from these talks is to maintain the status quo."
Voices at home also have begun to question Netanyahu's commitment to peace. On Wednesday, Yuval Diskin, a former director of Israel's Shin Bet internal security service, said time was running out for a peace deal. The alternative, he warned, was plunging into a single binational state in which Arabs ultimately outnumber Jews. As the man responsible for battling Palestinian militants for many years, Diskin's comments carry added weight in security-obsessed Israel.
"We need an agreement now, before we reach a point of no return from which the two-state solution is not an option any longer," Diskin told the Geneva Initiative, an Israeli-Palestinian peace organization. "It doesn't seem like the current government is trying to change the direction of the settlement enterprise."
In perhaps his toughest criticism of Netanyahu, he said the unresolved conflict with the Palestinians posed a bigger threat to Israel than Iran's nuclear program. Netanyahu believes Iran is trying to build a nuclear weapon and has sparred with Kerry over the international community's recent nuclear deal with Tehran, which insists its atomic program is for peaceful purposes.
Netanyahu, for his part, has dismissed the criticism. Officials in his office say Diskin is naively underestimating the threat of a nuclear-armed Iran. And at his appearance with Kerry Thursday, Netanyahu accused the Palestinians of "grandstanding" and called for serious, sustained negotiations.
The Palestinians seek all of the West Bank, the Gaza Strip and east Jerusalem as parts of their future state, with small adjustments through negotiated land swaps.
Netanyahu rejects any return to Israel's pre-1967 lines and has indicated he wants to keep control of large parts of the West Bank and all of east Jerusalem. He says the core of the dispute is not land claims, but a Palestinian refusal to recognize the Jewish people's ancient connection to the land.
In an editorial Friday, the Haaretz newspaper said Netanyahu was probably only going through the motions of negotiations to reduce international pressure, and would only act under such pressure. "The Americans should present a plan for borders between Israel and a Palestinian state. Without this Netanyahu will not advance," the paper wrote.
Kerry this week took a small step in that direction, arriving with his security adviser, retired Gen. John Allen, to present some bridging proposals for guaranteeing Israeli security in the West Bank. The idea, American officials say, is that by easing Israeli concerns, other issues, such as borders, can then fall into place. No details about the proposals were released.
The Palestinians gave the focus on security a cool reception.
"It is clear that Israel is trying to define its strategic security interests first, and then to draw the political borders in accordance with these security needs," said Yasser Abed Rabbo, a senior Palestinian official. "This is dangerous."
Yossi Beilin, the mastermind of landmark interim peace agreements in the 1990s, said the hard-line Netanyahu could argue over security matters for the next decade without resolution, and "the only way" forward is for all sides to discuss all concerns in parallel. "This has not happened," he said.
With the gaps so wide, Beilin said the Americans will have to soon start thinking about a Plan B. "Otherwise, there will be no plan whatsoever. This is the worst case scenario."
It is possible that the Americans will seek an extension in the talks. Beilin believes that with a final deal impossible, the best hope is for an interim agreement giving the Palestinians independence in temporary borders.
But the Palestinians reject any interim solution, fearing it could become permanent.
Instead, they have threatened to resume a campaign to win diplomatic recognition at the United Nations, in defiance of Israel. They have also begun floating the idea of seeking an international conference, along the lines of the Geneva talks that yielded the recent deal with Iran. And looming in the background is the constant fear of a third Palestinian uprising against Israeli occupation.
Beilin said it was impossible to say which scenario would unfold, predicting only "bad things which usually we don't know in advance."