Treason
"Whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason and shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States."
18 U.S. Code § 2381 https://www.law.cornell.edu/uscode/text/18/2381.
Misprision of treason
"Whoever, owing allegiance to the United States and having knowledge of the commission of any treason against them, conceals and does not, as soon as may be, disclose and make known the same to the President or to some judge of the United States, or to the governor or to some judge or justice of a particular State, is guilty of misprision of treason and shall be fined under this title or imprisoned not more than seven years, or both."
18 U.S. Code § 2382 https://www.law.cornell.edu/uscode/text/18/2382.
Rebellion or insurrection
"Whoever incites, sets on foot, assists, or engages in any rebellion or insurrection against the authority of the United States or the laws thereof, or gives aid or comfort thereto, shall be fined under this title or imprisoned not more than ten years, or both; and shall be incapable of holding any office under the United States."
18 U.S. Code § 2383 https://www.law.cornell.edu/uscode/text/18/2383.
Seditious conspiracy
"If two or more persons in any State or Territory, or in any place subject to the jurisdiction of the United States, conspire to overthrow, put down, or to destroy by force the Government of the United States, or to levy war against them, or to oppose by force the authority thereof, or by force to prevent, hinder, or delay the execution of any law of the United States, or by force to seize, take, or possess any property of the United States contrary to the authority thereof, they shall each be fined under this title or imprisoned not more than twenty years, or both."
18 U.S. Code § 2384 https://www.law.cornell.edu/uscode/text/18/2384.
Advocating overthrow of Government
"Whoever knowingly or willfully advocates, abets, advises, or teaches the duty, necessity, desirability, or propriety of overthrowing or destroying the government of the United States or the government of any State, Territory, District or Possession thereof, or the government of any political subdivision therein, by force or violence, or by the assassination of any officer of any such government; or
Whoever, with intent to cause the overthrow or destruction of any such government, prints, publishes, edits, issues, circulates, sells, distributes, or publicly displays any written or printed matter advocating, advising, or teaching the duty, necessity, desirability, or propriety of overthrowing or destroying any government in the United States by force or violence, or attempts to do so; or
Whoever organizes or helps or attempts to organize any society, group, or assembly of persons who teach, advocate, or encourage the overthrow or destruction of any such government by force or violence; or becomes or is a member of, or affiliates with, any such society, group, or assembly of persons, knowing the purposes thereof—
Shall be fined under this title or imprisoned not more than twenty years, or both, and shall be ineligible for employment by the United States or any department or agency thereof, for the five years next following his conviction.
If two or more persons conspire to commit any offense named in this section, each shall be fined under this title or imprisoned not more than twenty years, or both, and shall be ineligible for employment by the United States or any department or agency thereof, for the five years next following his conviction.
As used in this section, the terms “organizes” and “organize”, with respect to any society, group, or assembly of persons, include the recruiting of new members, the forming of new units, and the regrouping or expansion of existing clubs, classes, and other units of such society, group, or assembly of persons."
18 U.S. Code § 2385 https://www.law.cornell.edu/uscode/text/18/2385.
Recruiting for service against United States
"Whoever recruits soldiers or sailors within the United States, or in any place subject to the jurisdiction thereof, to engage in armed hostility against the same; or
Whoever opens within the United States, or in any place subject to the jurisdiction thereof, a recruiting station for the enlistment of such soldiers or sailors to serve in any manner in armed hostility against the United States—
Shall be fined under this title or imprisoned not more than five years, or both."
18 U.S. Code § 2389 https://www.law.cornell.edu/uscode/text/18/2389.
Enlistment to serve against United States
"Whoever enlists or is engaged within the United States or in any place subject to the jurisdiction thereof, with intent to serve in armed hostility against the United States, shall be fined under this title or imprisoned not more than three years, or both."
18 U.S. Code § 2390 https://www.law.cornell.edu/uscode/text/18/2390.
There's also a couple of others which may be of interest, see 18 U.S. Code Ch. 115 (https://www.law.cornell.edu/uscode/text/18/part-I/chapter-115.
While I would argue that seeking to overthrow the government is waging war against the US and fits the constitutional definition of treason.
However, it’s good to see that such an act is illegal even if I interpret the passage too strictly.