"interfering by word or deed with the defense of the United States or political processes and public opinions thereof"
A little bit of American history. After Pearl Harbor, the naturalization of enemy aliens was suspended for a time.
The myth popularized by the left is that after Pearl Harbor the United States began randomly going after Japanese-Americans because of racism. The actual reality is that the United States began relocating "enemy aliens" in the West Coast, which meant Germans, Japanese and Italians who were not United States citizens. Race wasn't the issue. Fear of an invasion was.
Executive Order 9066 is what the left loves talking about. And it's bringing up 9066 in reference to Trump's comments. But far more relevant are Presidential Proclamations 2525 through 2527.
Let's start with FDR's Presidential Proclamation 2525 after Pearl Harbor. It applied to the Japanese, 2526 to the Germans, 2527 to the Italians. But otherwise they were basically the same. Trump actually referenced these on Good Morning America as the basis for his proposals.
WHEREAS it is provided by Section 21 of Title 50 of the United States Code [11 F. C. A., tit. 50, § 21] as follows: "Whenever there is a declared war between the United States and any foreign nation or government, or any invasion or predatory incursion is perpetrated, attempted, or threatened against the territory of the United States by any foreign nation or government, and the President makes public proclamation of the event, all natives, citizens, denizens, or subjects of the hostile nation or government, being of the age of fourteen years and upward, who shall be within the United States and not actually naturalized, shall be liable to be apprehended, restrained, secured, and removed as alien enemies..."
FDR was quoting the law circa 1798. Specifically, "An Act Respecting Alien Enemies". The more relevant one at present is the Alien Friends Act. But since FDR was dealing with a straightforward declared war, he went with the first of the Alien and Sedition Acts.
It's still the law today.
Whenever there is a declared war between the United States and any foreign nation or government, or any invasion or predatory incursion is perpetrated, attempted or threatened against the territory of the United States by any foreign nation or government, and the President makes public proclamation of the event, all natives, citizens, denizens, or subjects of the hostile nation or government, being of the age of fourteen years and upward, who shall be within the United States and not actually naturalized, shall be liable to be apprehended, restrained, secured, and removed as alien enemies. The President is authorized in any such event, by his proclamation thereof, or other public act, to direct the conduct to be observed on the part of the United States, toward the aliens who become so liable; the manner and degree of the restraint to which they shall be subject and in what cases, and upon what security their residence shall be permitted, and to provide for the removal of those who, not being permitted to reside within the United States, refuse or neglect to depart therefrom; and to establish any other regulations which are found necessary in the premises and for the public safety.
(R.S. § 4067; Apr. 16, 1918, ch. 55, 40 Stat. 531.)
But here's some of the key language in FDR's proclamation.
"All alien enemies are enjoined to preserve the peace toward the United States and to refrain from crime against public safety, and from violating the laws of the United States and of the States and Territories thereof; and to refrain from actual hostility or giving information, aid or comfort to the enemies of the United States or interfering by word or deed with the defense of the United States or political processes and public opinions thereof; and to comply strictly with the regulations which are hereby or which may be from time to time promulgated by the President."
FDR wasn't engaging in a random crackdown. He was alien residents to avoid the types of behaviors that have unfortunately become routine with Muslim groups in America. CAIR alone has repeatedly violated these terms.
Note the part about " interfering by word or deed with the defense of the United States or political processes and public opinions thereof;". This was a ban on engaging in propaganda. And effectively a ban on support for the enemy.
(13) No alien enemy shall be a member or an officer of, or affiliated with, any organization, group or assembly hereafter designated by the Attorney General, nor shall any alien enemy advocate, defend or subscribe to the acts, principles or policies thereof, attend any meetings, conventions or gatherings thereof or possess or distribute any literature, propaganda or other writings or productions thereof.
Now, here's the interesting part, as far as the debate over guns and the no-fly list is concerned.
(5) No alien enemy shall have in his possession, custody or control at any time or place or use or operate any of the following enumerated articles:
b. Weapons or implements of war or component parts thereof.
e. Explosives or material used in the manufacture of explosives.
f. Short-wave radio receiving sets.
g. Transmitting sets.
h. Signal devices.
i. Codes or ciphers.
k. Papers, documents or books in which there may be invisible writing; photograph, sketch, picture, drawing, map or graphical representation of any military or naval installations or equipment or of any arms, ammunition, implements of war, device or thing used or intended to be used in the combat equipment of the land or naval forces of the United States or any military or naval post, camp or station.
Radios and flashlights were in fact confiscated from German, Japanese and Italian Americans. This may seem irrational in hindsight, but remember we didn't know what to expect back then, and we were thinking that the United States might face something like the conditions that existed in the UK at the time. Which meant that spies signaling bombers represented a real threat.
And there was a hell of a flight ban.
(6) No alien enemy shall undertake any air flight or ascend into the air in any airplane, aircraft or balloon of any sort whether owned governmentally, commercially or privately, except that travel by an alien enemy in an airplane or aircraft may be authorized by the Attorney General, or his representative, or the Secretary of War, or his representative, in their respective jurisdictions, under such regulations as they shall prescribe.
(12) No alien enemy shall enter or be found in or upon any highway, waterway, airway, railway, railroad, subway, public utility, building, place or thing not open and accessible to the public generally, and not generally used by the public.
Much of this proved unnecesary during WW2. But it was a legacy from WW1 in which German agents carried out a variety of terrorist attacks in the United States, including one that seriously damaged the Statue of Liberty.
There were a number of these proclamations during WW2 and even afterward from FDR and even Truman. And while they arguably went too far in addressing a threat that never really materialized because the United States applied the full might of its military capabilities and defeated the enemy, we inarguably have not gone nearly far enough in dealing with an enemy who presents more of a domestic terrorist threat than an international military threat.