On Tuesday, five days after the shooting rampage at Chattanooga and minutes after delivering a speech at the Veterans of Foreign Wars convention, President Barack Obama ordered all American flags on federal grounds to be lowered to half-staff for the rest of the week to honor the five service members killed at a naval reserve center in Chattanooga, Tenn.

At the Veterans of Foreign Wars convention, Obama defended his Iran nuclear deal, called for more military spending, and criticized Republicans for relying too heavily on military force and threats instead of diplomacy.

The president, facing growing criticism from conservatives and some veterans for not ordering flags to be at half-staff; sought to make amends by eulogizing each of the four Marines and the one sailor killed by a gunman in Chattanooga. According to Obama, Tom Sullivan was "everything that a Marine should be." Skip Wells was so devoted to the Marine Corps that he wore his dress blues to his home town's Fourth of July parade. David Wyatt led with courage in Afghanistan and mentored comrades with post-traumatic stress disorder. Carson Holmquist loved his wife, Jasmine, and their 2-year-old son. Randall Smith, the sailor, was a high school baseball star with two young daughters he called "little princesses," reports The Washington Post.

But even as he spoke, the president faced stinging criticism that he hadn't acted swiftly enough.

"Oh one more thing, lower the FLAG!!!!!!!! Sir," former Navy SEAL Marcus Luttrell, author of the best-selling book "Lone Survivor," wrote on his Facebook page, according to Journal Star.

Soon after, House Speaker John A. Boehner and Senate Majority Leader Mitch McConnell lowered the flag to half-mast on the Capitol grounds.

Obama has recently faced a lot of criticism on the Iran deal, with critics saying that tougher sanctions and threats of force would have been more effective in bending Iranian will.

In his VFW speech, Obama answered his critics by saying his more measured and diplomatic approach had produced results. "Instead of chest-beating that rejects even the idea of talking to our adversaries - which sometimes sounds good in sound bites, but accomplishes nothing - we're seeing that strong and principled diplomacy can give hope of actually resolving a problem peacefully," Obama said, according to the Houston Chronicle.