Future wars? Invasions USA

The 'surprise' invasion of Ukraine by Russia has invigorated discussion of the need for civilians armed with military weapons, as listed in the United States Constitution: The Biggest Case for the 2nd Amendment Is Happening Right No - Firearms News Are there plausible threats of invasion?
I will boldly assert that the United States could (not will be) invaded by Mexico, China or by an evil alliance.
The rationales for Mexico include prior territorial claim, mistreatment of immigrants and re-opening their drug market. Argentina invaded the Falkland Islands in 1982 with a territorial claim based on a sighting of the island by a French or Spanish navigator. Argentina ignored the stronger claim of British colonization in 1840 and continuous occupation to this day. Argentina invaded despite Britain being a nuclear power. Mexico colonized the present states of California, Arizona, New Mexico, Colorado and Texas. According to Mexican maps as recent as 1948, these regions were 'temporarily' ceded to the United States at the end of the Mexican War.
Italy invaded Ottoman Libya, in 1911, based on prior colonization by the Roman Empire and the mistreatment of Italian agrarian colonists allowed in by the Ottoman Turks. We have millions of legal and illegal immigrants from Mexico in the United States. While legal immigrants take a loyalty oath, we witnessed many Mexican flags being waved in the USA in anticipation of the 2016 Presidential election.
Great Britain sold opium in China for tea and fought two or three opium wars in the nineteenth century to keep their market open when such sales were outlawed by the Chinese government. Should the USA close the southern border, or end the drug war, the cartels might be tempted to re-open their market by force of arms. Otto von Bismark united multiple kingdoms in Germany to create an Empire and invade France in 1870. This is an unlikely scenario that would certainly take us by surprise.
The enmity of China for the United States is evidenced by both the supply of drug precursor chemicals to the Cartels and the free departure of infected Chinese from Wuhan after they were quarantined from the rest of China. China is contesting United States power in the Pacific with a larger navy, carrier targeting ballistic missiles and armed islands in the South China Sea. The immediate target is Taiwan.
The United States tariffs on Chinese products has hurt their economy. A loss of their drug sales my put them in domestic distress and needing an external war to pre-empt a civil war. China has a population of 1,300 million versus the 300 million in the United States. Tens of millions of Chinese men were born without hope for brides due to sex-selective abortions for decades. The Chinese merchant marine includes 1,200-foot container ships that can cross the Pacific in just five days. 
Another reason for a Chinese invasion is lebensraum. A 1970's study found sufficient water in China to feed just 500 million people indefinitely. North America could provide much needed space for Chinese farmers.
So I believe invasion is a plausible reason for civilian ownership of military arms. That is in addition to home defense and domestic discord.
​Best regards, Rick Kester