WASHINGTON – Syrian President Bashar Assad sent U.S. President Barack Obama a secret proposal for peace with Israel in 2010, which was also shared with Prime Minister Benjamin Netanyahu, former Secretary of State John Kerry writes in his new memoir published Tuesday.

According to Kerry, Netanyahu found the proposal “surprising” because it showed that Assad was willing to make more concessions than in previous negotiations.

The letter was drafted by Assad a year before the start of Syria's civil war; Syria and Israel did engage in American-mediated negotiations up until early 2011, but eventually did not reach any agreements or understandings.

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In his book “Every Day is Extra,” Kerry writes at length about Syria, which he describes as an “open wound” left behind by the Obama administration and an issue that he thinks about “every day.”

According to Kerry, in 2009, while he was chairman of the Senate Committee on Foreign Relations, he visited Damascus as part of a Middle East tour and held his first long meeting with Assad, who by then had been in power for a decade.

“In our first meeting, I confronted him about a Syrian nuclear power plant that Israel had famously bombed,” Kerry wrote, referring to the Syrian nuclear reactor that then-Prime Minister Ehud Olmert’s government destroyed in 2007.

“The fact that this was a nuclear facility had been well established publicly. It was beyond dispute,” Kerry explains. Yet Assad, according to Kerry, denied those facts, even when the two men were left alone. “Assad looked at me in the eye and told me it wasn’t a nuclear facility, with exactly the same affect and intonation with which he said everything else. It was a stupid lie, utterly disprovable, but he lied without any hesitation,” Kerry writes.

During their next conversation, writes Kerry, he pressed Assad on his support for the Lebanese terror group Hezbollah, and the Syrian president replied that “everything is to be negotiated” – hinting that this policy could change as a result of negotiations with Israel.

Kerry notes that previous attempts to reach a peace agreement between Israel and Syria under the governments of Yitzhak Rabin, Shimon Peres, Ehud Barak, Olmert and Netanyahu (during his first term in the 1990s) had all ended in failure, but Assad was still interested in some sort of deal with Israel.

“Assad asked me what it would take to enter into serious peace negotiations, in the hope of securing return of the Golan Heights, which Syria had lost to Israel in 1967,” writes Kerry. “I told him that if he were serious, he should make a private proposal. He asked what it would look like. I shared my thoughts. He instructed his top aide to draft a letter from Assad to President Obama.”

In the letter, writes Kerry, Assad asked Obama to support renewed peace talks with Israel and stated “Syria’s willingness to take a number of steps in exchange for the return of the Golan from Israel.”

Kerry notes that “Assad’s father [Hafez Assad] had tried and failed to get the Golan back, so he was willing to do a lot in return.”

According to Kerry, immediately after the meeting with Assad he flew over to Israel and shared the information with Netanyahu, who had just recently returned to power after 10 years either out of politics or in the opposition. “The next day, I flew to Israel, where I sat down with Prime Minister Bibi Netanyahu and showed him Assad’s letter,” writes Kerry. “He was surprised that Assad was willing to go that far, significantly further than he’d been willing to go [previously].”

Kerry had mentioned the letter’s existence once before, in a New Yorker interview in 2015, but had not previously described his conversation with Netanyahu about it. Back in 2015, he said that Netanyahu eventually told the administration he could not make an agreement with Syria under the circumstances.

According to Kerry, after he showed Assad’s letter to Netanyahu, he brought it back with him to Washington. The Obama administration tried to test Assad’s seriousness by asking the Syrian leader to take “confidence-building measures” toward both the United States and Israel, including a cessation of some weapon shipments to Hezbollah. Yet Assad disappointed the administration by failing to follow through on his promises.

“I remember hearing that Assad was continuing with exactly the kind of behavior on Hezbollah that we told him needed to stop. It was disappointing but unsurprising,” writes Kerry.

Later in the book, Kerry describes Assad in very negative terms, reflecting on his conduct throughout the brutal civil war. “A man who can lie to your face four feet away from you can just as easily lie to the world after he has gassed his own people to death,” Kerry says.

Kerry also writes at length about deliberations within the administration on how to react to Assad’s use of chemical weapons against his people in the summer of 2013.

According to Kerry, he and most other senior national security officials around Obama advocated for a military strike against Assad, in line with Obama’s definition of chemical attacks as a “red line.” But Obama hesitated – especially after it became evident that such a step would not receive overwhelming support in Congress.

Kerry concludes his chapter on Syria by writing that by the end of Obama’s term, and as Donald Trump was preparing to enter the White House, “diplomacy to save Syria was dead, and the wounds of Syria remained open. I think every day about how we might have closed them and how the world might close them still.”

On Friday, excerpts from Kerry’s book related to his attempts to foster an Israeli-Palestinian peace accord as secretary of state were published by Jewish Insider. In his memoir, Kerry also says he probably spent more time as secretary of state talking with Netanyahu than with any other world leader.