US defense secretary Chuck Hagel on Tuesday presented an austere vision of American global leadership in the 21st century, conceding that “imperfect outcomes may be the best we can expect” for terrorism and other pressing international challenges.

In a speech delivered to the Center for Strategic and International Studies that was tinged with ambivalence, Hagel pledged that the US would continue to embrace its role as a global superpower, rejecting both an “inward” turn among US politicians and a “hubris” that Hagel, a Vietnam veteran, called an “insidious disease.”

Amid the backdrop of an international crisis for Washington over pervasive US surveillance, Hagel said that the US “must make a far better effort to understand how the world sees us, and why. We must listen more. We must listen more.”

Terrorism, the pre-eminent focus of Hagel’s three predecessors, received barely a paragraph’s worth of attention in a 30-minute speech that mostly sought to frame US foreign leadership for “what comes after the post-9/11 era.”

Hagel lumped together “cyberactivists, terrorists and criminal networks, and non-state actors” as part of “short-term realities” that the US will confront – but, he said, will not eliminate.

“We must manage through these short-term realities as we strategically engage these complex problems – staying focused on our long-term interests and long-term objectives and outcomes,” Hagel said. “Imperfect outcomes may be the best we can expect, working our way toward the higher ground of possible solutions and resolutions.”

All of which contrasts with an embattled National Security Agency, which is under Hagel’s purview, that has recently come to argue that terrorism is a rising challenge. The NSA director, Keith Alexander, in answering the agency’s critics, has been arguing that terrorism is “the highest globally that it's been ever, over 15,000 people killed” in 2012, as Alexander testified last week to a House panel.

While the triumphalist rhetoric of the post-9/11 era was absent from Hagel’s speech, he did not address the contemporary contours of US counter-terrorism operations, such as special operations raids, drone strikes and capture missions, which have been displayed by US military and CIA forces in the past month alone, in Somalia, Pakistan and Libya.

The longer-term challenges Hagel outlined have been familiar themes of Obama administration speeches since former secretary of state Hillary Clinton declared that America was in the midst of a “Pacific century.” Hagel hailed a “renewed engagement in the Asia-Pacific region” while pledging the US to accepting “the astounding diffusion of economic power and sweeping demographic change,” including the rising influence of nations such as China, Turkey, India, Indonesia and Brazil.

Since Clinton’s declaration, US officials have struggled to demonstrate how what used to be called the “pivot to Asia” is substantial, or has not been dwarfed by the military’s immediate challenges in counter-terrorism.

Hagel suggested that a forthcoming Pentagon study, known as the Quadrennial Defense Review, will revamp the US defense posture in light of persistent challenges, automatic budget cuts and diminished political will to engage in peripheral conflicts.

Hagel did not outline the delay or cancellation of major weapons systems – such as the F-35 Joint Strike Fighter, the family of next-generation stealth attack jets that represent the most expensive weapons program in human history – but said the study will question “the assumptions and scenarios that guide how the military should organize, train, and equip our forces.” Hagel broached the politically treacherous subjects of a “tiered readiness system” for exhausted US troops and cutting pay and benefits for service members, which have represented the highest proportion of budget growth since 9/11.

As an apparent guide to the “imperfect" solutions the US will offer in the future, Hagel pointed to the recent initial destruction of Syria’s chemical weapon production equipment, an unexpected international development spurred by President Obama placing the US military on the precipice of bombing Syria.

Hagel, who was lambasted before and during his Senate confirmation hearings for alleged softness on Iran, praised the “diplomatic path” to a potential resolution of the Islamic Republic’s nuclear program, but said the US would not change its military posture in the Middle East during negotiations.

“We will maintain a strong and ready military presence in the Persian Gulf, and the broader Middle East, to deter Iran’s destabilizing activities, and to work with and protect our allies and our interests,” Hagel said.