President-elect Donald Trump has selected Rep. Mike Waltz to serve as White House national security adviser in his incoming administration.

Waltz, a combat-decorated Green Beret, was asked by Trump, 78, to serve as his principal adviser on all national security issues on Monday, a source confirmed to The Post.

The Wall Street Journal first reported the president-elect’s decision to tap the Florida Republican for the key White House role.

The position does not require Senate confirmation, allowing Waltz to step into the position as soon as Trump is inaugurated on Jan. 20.

Waltz, 50, has been outspoken about the US threat from China as a member of the House Foreign Affairs Committee.

“The Chinese are on the march,” the congressman warned last year, during an appearance on “Fox & Friends.” “We need to understand that within the next few years, they may make a move the likes of which we have never seen in the world.”

Waltz, who is also a member of the House China Task Force, has argued that the US military is not ready for an armed conflict with the US adversary in the Indo-Pacific region – noting in the May 2023 interview that US warships are double the average age of ships in the Chinese navy.

The incoming national security adviser has also slammed the Harris-Biden administration allowing a Chinese spy balloon to float over the entire continental US last year, calling it America’s “Sputnik moment.”

“The Chinese spy balloon has drastically changed Americans’ sense of security,” he wrote in a February 2023 op-ed, comparing the incident to when the Soviet Union beat the US in 1957 to become the first nation to launch a satellite into orbit.

Florida’s 6th Congressional District representative has also been critical of the Harris-Biden administration handling of Iran’s efforts to assassinate Trump.

“These plots from Iran are ongoing. And when [President Joe] Biden says nothing, [Vice President Kamala] Harris says nothing, the [Justice Department] tries to bury it, what message does Iran get? They get that we can keep trying to take Trump out and have no consequences,” Waltz told Fox News’ “Sunday Morning Futures” in August.

“They’re trying to kill him. And we know from the intelligence community Iran doesn’t want Trump back,” he added.

Waltz has panned the federal investigations into the July 13 assassination attempt against Trump in Butler, Pa., suggesting that federal agencies are taking too long to definitively determine whether 20-year-old would-be assassin Thomas Matthew Crooks acted alone.

“We’ve heard both the Secret Service and the FBI kind of phrase it in different ways — that everything they’ve seen he acted alone and that they have yet to find any co-conspirator … I find that hard to believe, and I want to see where’s the proof,” he told The Post in August.

“This isn’t an isolated incident that we could just take years to really take our time and unpack,” Waltz added. “There are ongoing threats as we speak. So yeah, I’m frustrated at how slow and how little we’ve learned.”

As Trump’s national security adviser, Waltz’s portfolio is sure to include Russia’s war in Ukraine and Israel’s fight against terror groups Hamas and Hezbollah in the Middle East.

Waltz, who was at first a strong proponent of Washington funneling military aid to Kyiv, has recently questioned whether continued arms and money shipments to the former Soviet state are in “America’s interest,” according to Reuters.

Waltz has suggested that the resources going to Ukraine may be off going to counter China in the Indo-Pacific.

He told NPR earlier this month that Trump’s pledge to immediately start peace negotiations between Ukraine and Russia is “perfectly reasonable” – further suggesting that the US could take “the handcuffs off of the long-range weapons we provided Ukraine” if Russian President Vladimir Putin refuses to end his war of aggression.

Like Trump, Waltz has also pushed for NATO allies to spend more on defense.

Waltz served in the US Army and National Guard for 27 years, only retiring during his second term in Congress.

He served combat tours in Afghanistan, the Middle East and Africa during his time in the military.

Waltz has also served as defense policy director for former Defense secretaries Donald Rumsfeld and Robert Gates.

The Trump campaign would not confirm to The Post that the president-elect has formally selected Waltz.

“President-Elect Trump will begin making decisions on who will serve in his second Administration soon. Those decisions will be announced when they are made,” Trump-Vance transition spokeswoman Karoline Leavitt said in a statement.

The Post has reached out to Waltz for comment.