Even before Israel’s ground invasion of Gaza began in late October, Vice President Kamala Harris’s national security adviser, Phil Gordon, feared that neither the Israeli military strategy nor key parts of the planned U.S. response would work.

Gordon worried that the only way to accomplish Israel’s goal of destroying Hamas entirely was to destroy Gaza along with it, with all the humanitarian tragedy that would entail, according to a person close to him who spoke on the condition of anonymity to discuss private conversations. Gordon did not believe the United States could influence Israeli Prime Minister Benjamin Netanyahu, whom he had dealt with during Israeli-Palestinian peace talks a decade earlier, the person said.

It is widely expected that Gordon would be the national security adviser in a Harris White House, should she win, and his personal views, which have not been previously reported, have largely aligned with Harris’s as the Israel-Gaza war has unfolded, according to several people familiar the matter who spoke on the condition of anonymity to describe a private relationship. The two have worked hand-in-hand to formulate Harris’s remarks at numerous inflection points in the war, providing clues as to how she could reshape U.S.-Israel policy if she wins the presidency.

Harris would probably conduct a full analysis of U.S.-Israel policy to determine what is working and what is not, according to several people familiar with her thinking, with Gordon leading the effort. It is unclear what would come of that process, but those familiar with conversations between Harris and Gordon say she could be open to imposing conditions on some aid to Israel, a policy that President Joe Biden has largely rejected.

Biden has taken some steps that Harris could build on to pursue such a policy. In February, Biden issued a memorandum requiring countries that receive U.S. weapons to adhere to certain standards, including abiding by international law and facilitating transport of U.S. humanitarian assistance, which critics say the president has not enforced. He also briefly suspended a shipment of 2,000-pound bombs this year.

The Israel-Gaza war has deeply divided Democrats since Hamas’s Oct. 7 attack, when militants killed about 1,200 people and took some 250 hostage. Israel’s retaliatory military campaign has killed more than 40,000 Palestinians, according to the Gaza Health Ministry, creating a humanitarian crisis and widespread hunger in the enclave.

Since becoming the Democratic nominee, Harris has faced pressure from activists to break from Biden’s Israel policy — but she has declined, not least because she is still his vice president.

But if she wins the Oval Office, she could set her own course. And as she formulates her foreign policy, Gordon has become one of her closest and most trusted advisers, helping to guide her through issues from the Middle East to the war in Ukraine.

Harris’s office said it would not discuss her potential policies should she become president. “We are not going to address hypothetical policy questions. She remains the Vice President of United States and stands by the Biden-Harris Administration policies,” Dean Lieberman, Harris’s deputy national security adviser, said in a statement. “The Vice President has made clear she will always ensure Israel has what it needs to defend itself from Iran and Iran-backed terrorists. She will never leave Israel unable to defend itself.”

While Harris has not articulated the specifics of her foreign policy, she is expected to largely continue Biden’s approach in many areas if she wins, including supporting Ukraine against Russia, pushing back against China’s assertiveness and seeking to build international alliances.

The area where Harris is most likely to differ from Biden, allies and analysts say, is on Israel. Despite her public support for Biden’s position, her private comments and concerns as the war has unfolded suggest she would be open to challenging Israel more directly, according to people familiar with her views who spoke on the condition of anonymity to discuss private conversations.

“The best-developed [policy] in terms of what could change is on the Middle East, because they know what’s not working,” said Ivo Daalder, a former U.S. ambassador to NATO who has known and worked with Gordon for decades. “There is plenty of evidence that a Harris administration and Phil would urge a fresh look at how we approach our overall Middle East policy, which they’re pretty clear now has to have an end state for the Palestinians at its core.”

Biden also supports a Palestinian state, but many activists say he has done little to promote it or to hold Netanyahu accountable for undermining its viability. Several current and former administration officials also said Harris has spoken more forcefully and explicitly about the need for a Palestinian state and self-determination.

Gordon’s résumé is in many ways typical of Washington insiders. He served as director of European affairs at the National Security Council under President Bill Clinton, then as assistant secretary of state under President Barack Obama, eventually becoming a Middle East specialist in the White House during Obama’s second term.

One former official joked that Gordon stands out because he is not part of the “pale, male and Yale” crowd that composes much of the U.S. Foreign Service. Gordon graduated from Ohio University before earning a PhD from the Johns Hopkins School of Advanced International Studies. That scholarly background, associates say, informs much of his methodical, dispassionate and even academic approach to foreign policy.

While Gordon’s former and current colleagues say he is not political, he was one of the first people to join Obama’s 2008 campaign, even as much of the Democratic establishment favored Hillary Clinton at the time. In 2019, Gordon became an informal foreign policy adviser to Harris’s ill-fated presidential campaign before advising Pete Buttigieg.

“Phil finds candidates he believes in,” said Frank Lowenstein, a former State Department official who has worked with Gordon. “He makes up his own mind about people he thinks would make great presidents and gets on board early.”

When Biden won, early supporters or longtime advisers received most of the top foreign policy jobs. Gordon became Harris’s deputy national security adviser and ascended to the top foreign policy job in her office in early 2022.

While Harris and Gordon did not initially have a strong personal relationship, associates say they have steadily become closer as the vice president has taken on a more prominent foreign policy role. She has met with European leaders as part of the administration’s effort to build a pro-Ukraine coalition, and she has traveled several times to southeast Asia to bolster alliances against China.

In many ways, Harris’s view of foreign policy is informed by her background as a prosecutor, according to aides and allies. She often focuses on whether countries are abiding by international humanitarian law and the “rules-based order” — an approach that can be particularly thorny when it comes to Israel.

That lawyerly approach has informed many of Harris’s most noteworthy comments about the war, including an assertion that Israel has a right to defend itself “but it matters how” and a statement that there are “no excuses” for not allowing more aid into Gaza.

Unlike Biden, Harris has not stressed or even publicly noted publicly that Hamas embeds its fighters among civilians — not because she does not believe it, but to avoid giving Israel cover for the high casualty rate, according to two people familiar with the thinking who spoke on the condition of anonymity to discuss private strategy. She has strongly condemned Hamas for a litany of other actions, including sexual violence on Oct. 7 and killing civilians.

Still, the specifics of how Middle East policy would change under Harris remain unclear. Much depends, of course, on whether the Israel-Gaza war is still raging. And several Middle East veterans cautioned that changing U.S. policy toward Israel can be politically difficult.

Aside from imposing conditions on aid, there are other steps the United States could take to change the nature of its relationship with Israel. They include legally recognizing rulings from international bodies, including a recent one from the International Court of Justice, which in July said Israel should end its occupation of Palestinian territory, evacuate existing settlements, stop building new ones, and pay reparations to Palestinians who have lost land and property.

Lieberman said Harris “will continue to stand up against anti-Israel bias in international organizations.” He added that Harris has been clear that her priority is finalizing the cease-fire and hostage release deal that she and Biden have been seeking for months, and that “more must be done to protect Palestinian civilians and to deliver humanitarian assistance, and international humanitarian law must be upheld.”

For now, Harris opposes cutting off offensive weapons to Israel, something many progressives want. A group of pro-Palestinian activists in Michigan that Harris briefly spoke to this month urged an arms embargo of Israel after the interaction. But Gordon, in a rare statement from his official X account, clarified the following day that Harris did not support such a policy.

“@VP has been clear: she will always ensure Israel is able to defend itself against Iran and Iran-backed terrorist groups. She does not support an arms embargo on Israel. She will continue to work to protect civilians in Gaza and to uphold international humanitarian law,” Gordon wrote.

If Harris wins the White House, Gordon may have a bigger impact on foreign policy than Biden’s aides do. Biden came into the presidency with more than 50 years of foreign policy experience, including as chairman of the Senate Foreign Relations Committee, and he is supremely confident in his own judgment, according to numerous current and former White House officials.

On certain issues, including his reluctance to withhold aid from Israel or to allow Ukraine to strike deeper into Russia, Biden has been immovable, much to the frustration of some aides. Having a president so knowledgeable and confident of his own instincts can be an asset, since it provides clarity and direction, they say, but it also carries risk.

“That experience is double-edged sword because Biden always thought he knew more than everybody and was intransigent,” one outside adviser said. “Most presidents use the policy process to present them with choices and manage debate and make a decision. I expect Phil would play the role of honest broker among a group of advisers.”

Gordon, by nearly all accounts, is the person Harris trusts most when it comes to global affairs, and his quiet, deliberate style has endeared him to her. Former associates said he is loyal and has no problem voicing his opinions in private but will fully back the administration’s policy in public.

That approach was evident when Israel launched its ground invasion of Gaza in October. Gordon was at a meeting with Sullivan and several former national security aides, according to three people familiar with the meeting.

While the other officials were almost entirely focused on dissuading Israel from a full-scale assault, Gordon was already asking about the “day after,” one of the people recalled. How does this end? Gordon asked of the military campaign. How will the United States advance a two-state solution once the war is over?

The questions struck some in the meeting as overly academic and theoretical, given that the war was just beginning, according to one of the participants. But they ended up being prescient. And now everyone is asking about “the day after.”