Republican presidential candidate Donald Trump in Colorado Springs Saturday Sept. 17 2016.

 (AP Photo/ Evan Vucci)

Republican presidential Donald Trump touched on immigration, energy, taxes, health care and trade issues Saturday night during a brief appearance in Colorado Springs. 

He promised to create jobs and build a border wall with Mexico.

"We also have the support of 16,500 Border Patrol officers. Earlier today, I had a chance to spend some time with the victims of illegal immigrant violence – these are people from all races and backgrounds. They are all united by one common fact: their government failed them in its most basic duty," Trump said.

He brushed off criticism that he hasn’t revealed his plans to defeat ISIS, by invoking a decorated World War II general.

"Can you imagine Gen. Douglas MacArthur saying at a news conference, well that’s a very good question Jim. We’re going to hit em from the front on October 7.”

If elected, he also said he'd lift restrictions on oil and gas development.

At the Trump rally in Colorado Springs Sept. 17 Bill Young of California says he travels around to Trump events to sell T-shirts.

(Rachel Estabrook/CPR News)

“It’s going to be an amazing unlocking, too, believe me. This one action alone will raise the quality of life for tens of millions of Americans. We’ll be a rich country again.”

Trump's opponent, Democrat Hillary Clinton, is campaigning on making the United States the world's clean energy superpower.

Trump also used his stopover to hit back at a former defense secretary who called him "beyond repair" when it comes to national security.

Robert Gates served under presidents of both parties. He wrote in the Wall Street Journal on Saturday that Trump is "stubbornly uninformed" about the world.

"He has expressed support for [...] for torturing suspected terrorists and killing their families; for Mr. Putin’s dictatorial leadership and for Saddam Hussein’s nonexistent successes against terrorism." Gates said in the piece. "Mr. Trump has been cavalier about the use of nuclear weapons. He has a record of insults to servicemen, their families and the military, which he called a 'disaster.' He has declared our senior military leaders 'reduced to rubble' and 'embarrassing our country' and has suggested that, if elected, he will purge them—an unprecedented and unconscionable threat."

Trump first swiped back on Twitter, then went further at the rally.

Trump said Gates "probably has a problem we don't know about" and claimed that he would be "so much better at what he's doing" than Gates.

He also called Gates "a nasty guy" and "an absolute clown."

"I don't like critics,” Trump said.

"This is our chance to replace a failed, corrupt and dishonest political establishment with a new government that answers to the citizens – not the special interests," Trump said in prepared remarks. "We can’t keep listening to the same people who created all of our problems in the first place."

Republican presidential candidate Donald Trump's plane in Colorado Springs Saturday Sept. 17 2016.

(Rachel Estabrook/CPR News)

Many of the Republican candidate’s fans at the event said they were energized by Clinton’s recent comments that half of Trump supporters could be put in a “basket of deplorables.” 

“Anybody deplorable enough to help Donald Trump?,” said Eric Barr, who recruited volunteers for Trump's campaign. Elsewhere, vendors sold T-shirts that said “Deplorable Me.”

In line for the rally, Rosie Cardona and her daughter Rose Frick of Castle Rock called Trump a straight shooter who tells is like it is.

The Trump plane pulled in while the soundtrack to the Harrison Ford movie "Air Force One" played in the background.

The Associated Press contributed to this report.