WASHINGTON - One more retired general in the incoming US administration now -- President-elect Donald Trump on Monday formally pick retired Marine Corps Gen. John Kelly to lead the Department of Homeland Security.

Kelly will become the third retired general to be tapped for the incoming Trump cabinet after retired Lt. Gen. Michael Flynn for national security advisor and retired Gen. James Mattis for Defense secretary.

As the DHS chief, he will be at the forefront of realizing Trump's campaign promise to build a wall between the US and Mexico, as well as crack down on undocumented immigrants.

"Gen. John Kelly's decades of military service and deep commitment to fighting the threat of terrorism inside our borders makes him the ideal choice to serve as our Secretary of the Department of Homeland Security," Trump said in a statement.

"He is the right person to spearhead the urgent mission of stopping illegal immigration and securing our borders, streamlining TSA and improving coordination between our intelligence and law enforcement agencies" Trump said.

"The American people voted in this election to stop terrorism, take back sovereignty at our borders, and put a stop to political correctness that for too long has dictated our approach to national security," Kelly said in a statement.

"I will tackle those issues with a seriousness of purpose and a deep respect for our laws and Constitution," Kelly said.

Kelly headed the US Southern Command until retiring in January after more than 45 years in the Marine Corps. In that role, Kelly oversaw the prison at Guantanamo Bay, Cuba and publicly butted heads with the Obama administration over its plan to close it, according to a TheHill news daily report.

He also served in combat in Iraq and spent a year as the head of US forces in that country.

A report last week said Trump is considering tapping as many as five generals for his cabinet, said the TheHill report.