This is correct but perhaps doesn't get at the issue of inviting a foreign power to intervene in an election at the core of US national sovereignty using methods deemed illegal both in the US and internationally. It's sort of like asking someone to break into the DNC headquarters to bug its communications, only without duct tape on the door locks and 1970's era listening devices, only you aren't asking Gordon Liddy and his crew to commit this crime for your benefit, but are asking this of the leadership of another nation, one with which we have a fraught relationship.
Here’s good way to think about what Trump just did, repeatedly, at his Wednesday press conference. Set aside all the troubling questions Trump won’t answer about Russian investment in his business projects, and about his advisers’ financial ties to Russian oligarchs, and about the growing consensus that Russian security services stole DNC emails, and about all the quos, like Trump threatening to abrogate NATO commitments, and his intent to dial back support for Ukraine independence, and his opposition to Russian sanctions. In other words, pretend none of the strange aromas engulfing his campaign were there and consider: Trump just coordinated with Russia in a way that would be illegal if Russia were a super PAC, in the hope that Russia will do something it would be illegal for a super PAC to do.
At Bloomberg, Noah Feldman explains why Trump's invitation is probably not a prosecutable crime. I defer to the experts on that. But Trump has openly asked Russia to cause crimes to be committed on behalf of his candidacy. What, one might wonder, would Putin ask of Trump in return?
Update: Some dare call it treason:
Donald Trump's call on Russia to hack Hillary Clinton's emails has shocked, flabbergasted and appalled lawmakers and national security experts across the political spectrum, with some describing his comments as "treason."......................
Few would argue Wednesday that what the Republican presidential nominee said will directly cause Russia to conduct more cyber-espionage against the U.S. than it already is doing. But several described Trump's statements as dangerous for America's global standing. Some echoed the Clinton campaign in calling the comments a threat to national security.
"It’s just one more example of the reckless and dangerous comments that Donald Trump makes that compromises American foreign policy objectives," said Sen. Ben Cardin of Maryland, the ranking Democrat on the Senate Foreign Relations Committee.
Leon Panetta, a former CIA director, said Trump's comments were "beyond the pale" because he was "in fact asking the Russians to engage in American politics." An aide to House Speaker Paul Ryan, who has endorsed Trump, added, meanwhile, that "Russia is a global menace led by a devious thug" and that it should stay out of the U.S. election.
Even as some Trump supporters insisted he was just joking, several national security experts said they could not recall another instance of a major party candidate calling on a foreign power to spy on a U.S. citizen, much less on a political opponent.
"Leaders who are serious about national security do not, even in jest, encourage foreign powers to spy on us," said Timothy Naftali, co-director of New York University's Center for the United States and the Cold War. "What Putin would take seriously, I suspect, is that Trump seems so eager to hurt Hillary Clinton that he doesn't care getting a little Russian help. On the other hand if there is some behind the scenes collusion between the Kremlin and Trump Tower, Putin must think Trump, at best, brazen or a fool for playing it all this way."
Evelyn Farkas, a former Obama administration official with expertise on Russia, added, "It's a pretty outrageous thing to do to anyone, and it feels somewhat treasonous."