Maintaining a Superpower is hard work, of course America meddles, and they should.
The issue isn't about what they do internationally, but what society is supported domestically. Maintain liberty at home, support your constitution and individual rights, it's then the job of foreign governments and their agencies to prevent U.S meddling, and, vice versa. That's how it goes.
Actually, the sovereignty of nations is accepted. The UN should intervene, when a regime tries to acquire recourses and political power in the world through the most reckless methods. There will always be war and parties will support parties. But this is an agenda.
May be. However, the UN has been feckless. If it were up to the UN nothing would had been done in Kosovo, in Afghanistan in fighting ISIS. Nothing was done when Russia walked into Crimea, when China expanded into the South Southern Sea. That in itself is the problem. These nations are feckless and have 1000 opinions, none of them willing to lead.
This is one of the reasons I support America. It has been a nation of action. If not for the U.S there would be many more wars in the world and we would have experienced at least one other World War, and who knows what? Now it's all state vs state, skirmishes, and proxy battles. The UN has little value now in my opinion in regards to military action, just as the WTO has little credibility in protecting fair trade and encouraging capitalism.