This week, Hillary Clinton made history by becoming the first female nominee for president of a major American political party. In doing so, she fended off a serious threat from Vermont Senator Bernie Sanders, a self-proclaimed socialist who has become a titanic force in the Democratic Party. Sanders has challenged Democratic orthodoxy on free trade, Middle East policy and the scope of executive power to conduct unlimited military campaigns under the auspices of the war against terrorism. In doing so he has exposed one of Clinton’s greatest vulnerabilities in a general election: Her judgment when conducting foreign affairs. Clinton’s record as a military hawk is well-known. She voted for the Iraq War as a senator. As secretary of state, she pushed for US intervention in Libya and lobbied President Obama to take military action against Bashar al-Assad in Syria. She was lukewarm about the nuclear deal with Iran. With respect to Israel, in March she gave a major policy speech to the American Israel Public Affairs Committee (AIPAC) without so much as mentioning the plight of the Palestinians – a point later highlighted by Sanders, a son of Jewish immigrants, during their debate in Brooklyn. Progressives, independents and liberal democrats who have been voting in large numbers for Sanders hold the keys for Clinton to defeat Donald Trump. If Clinton is to consolidate her support among these important constituencies, she must reassure them that despite her record, she is willing to follow in President Obama’s footsteps and not seek military solutions to every vexing foreign policy problem. To be sure, Clinton’s hawkish instincts fall within the mainstream of the foreign policy establishment. Yet in this election year she faces two problems. First, in the past two national elections, the Democratic base has embraced President Obama’s foreign policy doctrine, loosely defined as emphasizing negotiation and collaboration rather than confrontation and unilateralism. Sanders has projected a similar view of the United States’ role in the world. Second, Clinton’s opponent in the general election, Donald Trump, has consistently conveyed a message that America is taking on too much of a burden in providing global security for its allies and not receiving enough of the commercial benefit. This argument has gained traction in a Republican Party that increasingly sees endless military campaigns in the Middle East as a drain on American blood and treasure. Thus, Clinton’s reliance on hard power as a means of advancing American interests is a tough sell in an election year where voters seem to prefer retrenchment rather than military adventurism. Rather than embrace President Obama’s foreign policy of military restraint, Clinton signaled in a major foreign policy address last week that she would be doubling down on the conflict in Syria by imposing a no-fly zone – something the Obama administration has ruled out for fear of deepening America’s involvement in the Syrian civil war and risking escalation with Russia and Iran, the Assad government’s main patrons. Furthermore, Clinton has proclaimed that she would reaffirm her “unbreakable bond” with Israeli Prime Minister Benjamin Netanyahu. Fidelity to Israel’s security is a staple of all presidential campaigns, but Clinton has gone on record embracing an Israeli prime minister who repeatedly embarrassed President Obama, tried to torpedo his signature foreign policy achievement – the Iran nuclear deal – and paid only lip service to the peace process with Palestinians. Such positions put her at odds with Sanders’ supporters, who, like President Obama, are committed to Israel’s security but also recognize the tremendous toll the occupation and continued expansion of Israeli settlements take on American security interests in the Middle East and on Palestinian society. They would like to see the United States play a more evenhanded role. So far, Clinton has not shown any willingness to confront more hard-line Israeli policies that make peace harder to achieve. To defeat Trump, Clinton must not revert back to the US foreign policy status quo, which is grounded in the theory that military force and intervention hold the key to peace and prosperity – and has brought little in the way of either. During the more than two decades that US forces have been engaged in military action in the Middle East, militancy and instability have increased, not decreased. President Obama, to his credit, charted a different course. His insistence on negotiating with Iran, a longtime adversary, produced a landmark nuclear agreement – something that seemed inconceivable when President George W. Bush occupied the White House. Clinton needs to show that she is equally comfortable exercising restraint, and that she understands the limits of US power as well as its effectiveness – an understanding that forms the bedrock of the world view embraced by Sanders and Obama supporters. Amir Handjani is a fellow with the Truman National Security Project and Board Member of the Atlantic Council. He tweets @ahandjani