Washington says it is reviewing its push for a Middle East peace agreement as a spiral of tit-for-tat moves by Israel and the Palestinians took hard-won talks close to collapse.
US Secretary of State John Kerry, who has invested more than a year of intensive shuttle diplomacy in the talks process, said there were "limits" to the time Washington could devote to it.
"This is not open-ended," Kerry said during a visit to Morocco, adding that it was "reality check" time and he would evaluate with President Barack Obama what Washington does next.
"There are limits to the amount of time and effort that the United States can spend if the parties themselves are unwilling to take constructive steps," Kerry said.
The US top diplomat spoke to both Israeli and Palestinian leaders on Thursday in a desperate bid to bring the two sides back from the brink.
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But Palestinian president Mahmud Abbas rejected Kerry's appeals to withdraw the applications he signed on Tuesday to adhere to 15 international treaties, a Palestinian official told AFP.
And Israeli Prime Minister Benjamin Netanyahu ignored appeals to refrain from "unhelpful" tit-for-tat moves and asked officials to draw up a range of tough reprisals, Israeli media reported.
Kerry said Washington currently had an "enormous amount on the plate", highlighting negotiations with the Russians over Ukraine, talks with Iran on its nuclear program and the conflict in Syria, as other US priorities.
"Both parties say they want to continue, neither party has said they want to call it off; but we're not going to sit there indefinitely, this is not an open-ended effort," he said.
