US President Donald Trump urged North Korean leader Kim Jong-un on Sunday to “act quickly” and reach a deal with him on dismantling the country’s nuclear weapons program. “You should act quickly, get the deal done. See you soon!” he tweeted.

The tweet came just about 10 hours after the defense ministers of South Korea and the US announced the postponement of the allies’ wintertime combined air exercises. Trump sent a message that it was Kim’s turn to show his intent to come forward for a summit, now that he has shown his good faith by putting off the drills the North opposed strongly.

Trump also said in the tweet that “I am the only one who can get you where you have to be.” This is a reminder that he will take economic and other corresponding measures if the North makes progress on denuclearization. Economic prosperity in exchange for scrapping nuclear weapons programs is a proposal Trump has made consistently to North Korea, but it will not be easy to actualize.

Trump had summits with Kim twice, but they made little progress, only exposing big differences over how to eliminate the North’s nuclear programs.

Pyongyang wants the programs to be dismantled in stages and the US to take corresponding measures simultaneously. Washington wants both sides to agree first on an overall denuclearization schedule and then carry out specific plans accordingly. The North also demands the US guarantee the security of Kim’s regime and loosen its sanctions, while the US demands the North declare all of its nuclear facilities first.

For the two sides to find common ground, they need to compromise. If one side deceives the other, negotiations cannot move forward.

North Korea has accumulated know-how through decades of negotiations with the US. It always seeks an advantageous negotiating position by escalating its demands while expressing its willingness to hold dialogue.

It fixed the deadline for negotiations at the end of this year and has pressed the US persistently to come up with an “advanced” proposal. It expressed antipathy bluntly against the US-South Korea combined military exercises, the sale of high-tech weapons to South Korea by the US, and the deployment of the US’ new strategic weapons.

Now that the wintertime combined air exercises have been put off, it denounced a UN human rights resolution against it. A North Korean Foreign Ministry spokesperson even bluffed that “even if the North-US talks reopen in the future, the nuclear issue would never be discussed before the issue of withdrawing the US hostile policy to improve relations with us be brought up in the agenda for dialogue.”

In response to the latest tweet from Trump, North Korean Foreign Ministry adviser Kim Kye-gwan reiterated his government’s stance that the US must drop what the North sees as hostile policies to keep the negotiations alive. This is to pressure the US to guarantee the security of Kim’s regime and not to raise questions about human rights in the North. The North is fanning a war of nerves to make more room for discussion of the US guarantee of Kim’s regime within its nuclear negotiations.

But Pyongyang must know it may not get what it wants if it continues this attitude, even if its third summit with the US takes place before the end of the year. Especially due to the die-hard animosity between the US and North Korea and the difficulty of finding common ground in their negotiations. This is why both sides must patiently find points of accord for substantial progress.

In this light, Trump’s political reality is worrisome. He is running for reelection next November and has little to show to voters regarding nuclear negotiations with the North. To make matters worse, he is being cornered by the Congress’ open impeachment inquiry. His improvising style is worrying, too. He may be eager to highlight the North Korea issue as his foreign policy achievement. If so, a successful third summit with Kim could give him something to boast about.

Impatient to score political points, Trump may make bolder offers to bring Kim to the table. They may be bold enough to put South Korea at serious risk.

Solving North Korea’s nuclear issue through dialogue is the best possible way, but holding talks just for the sake of it or for a political show will only prolong and worsen the crisis.