The progressive candidates have signaled their desire to pursue a policy in which the United States reduces its military commitments overseas—what is usually called a “foreign policy of restraint.” The interesting question, though, is whether that is possible at an acceptable cost. Outside of the Middle East, the answer is almost certainly no. If they were to go further toward adopting a strategy of restraint whereby the United States does much less militarily around the world, they would have to make major sacrifices on alliances, nuclear proliferation, and spheres of influence that no Democratic commander in chief seems likely to want to make.

Thomas Wright: Buttigieg splits from the progressives on foreign policy

Two candidates for president—Bernie Sanders and Elizabeth Warren—have embraced the progressive-foreign-policy label. Reading their speeches and articles, two major themes stand out.

The first is that Sanders’s and Warren’s specific ideas to change U.S. foreign policy are focused on the Middle East. They oppose military intervention in Syria and Iraq. They support the Iran nuclear deal. They want to get tough with Saudi Arabia, going beyond simply ending U.S. support for the war in Yemen. Both favor an end to the war in Afghanistan, and both have questioned the extent of ongoing operations against terrorist networks. Sanders and Warren do differ over Israel—Sanders is very critical of Israel and has questioned U.S. aid, whereas Warren is generally seen as supportive of the alliance.

However, when you drill down, the two presidential candidates are difficult to pin down on whether they oppose military intervention on principle or, if not, under what conditions they might support it.

Sanders opposed the Vietnam War, the Gulf War, and the Iraq War of 2003, as well as numerous U.S. interventions in Latin America and the Middle East. However, he also voted for the Iraq Liberation Act of 1998 and later called Saddam Hussein “a brutal dictator who should be overthrown.” He opposed Operation Desert Fox, a bombing campaign in Iraq in 1998, primarily because it did not have congressional or United Nations approval, but also because he did not think it would bring about regime change. He voted for the 1999 Kosovo War and subsequently supported the NATO bombing campaign, even as he argued that President Bill Clinton’s failure to secure congressional support meant it was unconstitutional. He voted for the 2001 Authorization for Use of Military Force and did not oppose the 2011 intervention in Libya in its initial stages, when the sacking of Benghazi by Muammar Qaddafi’s forces seemed imminent.

Unlike Sanders, Warren never had to vote or comment on these interventions. She has been careful not to shed any light on her views on them since becoming a U.S. senator. However, Warren does have a track record from when she entered politics in 2012. In Warren’s first-ever speech on foreign policy, at Georgetown University in 2014, she implicitly criticized Obama for not being sufficiently sensitive to civilian casualties in his drone strikes. In 2014, she said that the defeat of ISIS should be the Obama administration’s top priority, but that the United States should avoid getting dragged into a war. She supported Obama’s air strikes in Iraq in 2014, while opposing his plan to train and equip Syrian opposition forces.