President Barack Obama arrives to deliver his speech at the 116th National Convention of the Veterans of Foreign Wars Tuesday in Pittsburgh.

PITTSBURGH — Denouncing “chest-beating” critics, President Barack Obama told a veterans group Tuesday that those who oppose the diplomatic agreement to rein in Iran’s nuclear program are some of the same people who were quick to want to go to war in Iraq and thought military action there would take only a matter of months.

“We’re hearing the echoes of some of the same policies and mindsets that failed us in the past,” Obama told the Veterans of Foreign Wars national convention. He argued that the Iran deal offers “a smarter, more responsible way to protect our national security.” Obama spoke one day after the U.N. Security Council unanimously endorsed the nuclear deal with Iran. The White House is mounting a massive outreach campaign to try to win over skeptics and avert a congressional attempt to scuttle the deal, dispatching top officials daily to television shows and Capitol Hill.

Obama told his audience there was “a lot of shaky information out there” about the deal, and he seemed eager to push back.

“The same politicians and pundits that are so quick to reject the possibility of a diplomatic solution to Iran’s nuclear program are the same folks who were so quick to go to war in Iraq and said it would only take a few months,” Obama said.

He said his administration had “done the hard and patient work of uniting the international community to meet a common threat. Instead of chest-beating that rejects the idea of talking to our adversaries, which sometimes sounds good in sound bites but accomplishes nothing, we’re seeing that strong, principled diplomacy can give hope of actually resolving a problem peacefully, instead of rushing into another conflict.”

Obama also addressed the problems at the Department of Veterans Affairs, which has been under scrutiny over wait lists and other shortcomings in the health system.

Obama said that while significant progress has been made at the troubled agency, “We’ve got to acknowledge our work is not done. We still have a big challenge” to keep up with the surge in veterans seeking care.

The military community has also been on edge over the killing of four Marines and a sailor last week in Chattanooga, Tenn. Obama has pledged a prompt and thorough investigation into an attack that authorities have blamed on a 24-year-old Kuwait-born man, and Obama said the nation was drawing strength from Chattanooga while sending an unmistakable message that the U.S. won’t give in to fear or attempts to change the American way of life.