- Trump is headed to the G20 summit in Germany
(CNN)Kim Jong Un just changed Donald Trump's presidency.
The North Korean dictator's first successful intercontinental ballistic missile test on Monday did more than shake up strategic calculations in the Pacific.
It presented Trump with his first real test on the global stage as he flies off to meet far more experienced leaders at the G20 summit in Germany, some of whom are ill-disposed to help him and don't have the US's best interests at heart.
It's a trip that will now be judged on Trump's capacity to secure not just international condemnation of North Korea's actions, but to advance US efforts to change the strategic calculation in Pyongyang.
The mission will test Trump's skill at wielding US power, building international coalitions behind American foreign policy goals and framing innovative policy approaches that haven't yet been tried and that don't fit neatly into the "America First" doctrine that is driving his foreign policy.
Forget the tweetstorms, slams at "fake news" journalists and morale boosting rallies before crowds who thrill to Trump's politically incorrect rhetorical blasts.
This is what being President is really about.
In one sense, the July 4 pyrotechnics from the isolated state ushered in an alarming new reality, one Trump is the first President to face -- the prospect that in theory, Pyongyang could soon hit the US with a nuclear-capable missile.
But what makes Trump's job so difficult is the unpalatable set of options available to try to halt North Korea's nuclear and missile programs. If those fail, an equally unpleasant option would await -- accepting the reality the United States is in Pyongyang's crosshairs.
In other words, Trump is under intense pressure to solve what may be an insoluble foreign policy problem.
He would have to decide how to contain the threat from the North Korean program or to deter the use of a weapon, effectively accepting that in theory at last Pyongyang had the US in the crosshairs.
"There is an argument to be made that everything has changed and nothing has changed," said Jim Walsh, senior research associate at the Massachusetts Institute of Technology Security Studies Program, adding that the test had demonstrated new North Korean capabilities and taken the US across a psychological and political threshold.
But Walsh said the options for the US to respond "really haven't changed. Today's options are no different from yesterday's options, and yesterday's options weren't very good."
Given that military attempts to halt North Korea's nuclear march all risk a horrific confrontation that could kill millions on the Korean peninsula and beyond, Trump has few alternatives but to seek a diplomatic outcome to the showdown with Pyongyang.
Yet there are few approaches that other presidents have not already tried.
One route the administration is taking is a familiar one -- seeking a Security Council condemnation of the test launch on Wednesday at the UN and new sanctions on the already heavily sanctioned North. US and South Korean forces are also conducting exercises in the region in response to the test.
Trump came to office slamming the "strategic patience" strategy pursued by the previous Obama administration on North Korea -- involving tough sanctions and a refusal to talk to Pyongyang until it renounces nuclear development.
But he has yet to diverge substantially from the approach of the last few administrations.
His preferred initial tactic was also a familiar one -- a charm offensive to convince Chinese President Xi Jinping, whom he will meet in Germany, to pressure Beijing's recalcitrant neighbor into halting its nuclear and missile programs.
But now the President, only three months after meeting Xi at his Florida resort, appears to have concluded that effort has failed, further narrowing his options.
"North Korea has just launched another missile. Does this guy have anything better to do with his life?" Trump tweeted after Monday's launch.
"Hard to believe that South Korea and Japan will put up with this much longer. Perhaps China will put a heavy move on North Korea and end this nonsense once and for all!"
On Wednesday, Trump added: "Trade between China and North Korea grew almost 40% in the first quarter. So much for China working with us — but we had to give it a try!"
There are differing interpretations as to how much Beijing has so far done to pressure the North Koreans, following its decision to halt coal exports to the Stalinist state and a temporary freeze on oil supplies.
And Washington may be overestimating China's capacity to change the behavior of the volatile North Korean leader.
Many experts also believe that China is reluctant to try the kind of prolonged oil embargo that could really pressure Kim because of a fear it could collapse his regime and ignite a chaotic situation on the peninsula. Beijing also has no interest in a solution that would lead to a unified Korea in alliance with the US on its borders.
Whatever China's motivations, however, it seems unlikely that its leaders will be swayed by Trump tweets, hence the need for a prolonged and comprehensive diplomatic push by the administration starting at the G20.
"This is really a good opportunity for the President to show leadership, and to show the type of leader he is," said Harry Kazianis, Director of Defense Studies at the Center for the National Interest, who argued that Trump's tweets were merely a type of "strategic signaling" not the extent of US policy.
If Trump's powers of persuasion with other world leaders fall short, he and his administration will be left with some tough decisions.
One option would be to expand secondary sanctions on Chinese firms that do business with North Korea to try to tighten an economic chokehold around Pyongyang.
"We really need to focus on the players in China, Chinese banks. the people that are aiding and abetting the money laundering," said Kazianis, who also advocates stepping up cybersecurity operations against Pyongyang's missile and nuclear programs.
Widening sanctions on China's firms is a logical next step, one of the few new approaches that the administration could pursue.
But such a move would also create a whole new foreign policy headache by triggering a sharp deterioration in relations with China, a scenario that could have unpredictable results and significantly increase regional tensions in Asia.
Another option for Trump -- actually talking to the North Koreans -- has been tried before, and is problematic, since Pyongyang has in the past agreed to nuclear freezes and walked away from the deal. Kim, having watched the demise of other dictators who gave away their nuclear programs, believes that his atomic weapons are the only guarantor of his survival.
"They will never give up their nuclear weapons program. They will never give up their missile program. That discussion is off the table," said Sue Mi Terry, a former CIA North Korea analyst, on CNN on Wednesday.
Whatever path he eventually chooses, it's clear that tough talk and tweets are unlikely to provide breakthroughs and that managing escalating tensions will consume the administration for as long as it is in office.
"The main danger here, contrary to some expectations, is not that North Korea is going to suddenly attack the US," Walsh said. "The danger is that there will be a war, but it will happen through miscalculation or misperception."