WASHINGTON >> President Donald Trump today invited South Korea’s new president to visit the White House after an election victory that could cause friction between the allies over how to deal with North Korea’s nuclear threat.

Trump wants to tighten an economic vise and has raised the possibility of military force as the North approaches the capability to threaten America with a nuclear-tipped missile. Moon advocates a less confrontational policy. As he took the oath of office today, Moon Jae-in said he was open to visiting Pyongyang under the right conditions to discuss its nuclear program.

In their phone call, Trump congratulated Moon on his election victory and his country’s “peaceful, democratic transition of power,” a White House statement said. The leaders agreed to strengthen the alliance. Moon accepted Trump’s invitation to visit at an “early date.” No specific timing was set.

South Korea’s past decade of conservative rule has encouraged smooth relations with the U.S. Moon’s more liberal approach could fuel tensions, as happened under a liberal South Korean government in the 2000s. The country hosts some 28,000 U.S. forces.

In a sign of Washington’s growing concern about the North, the CIA announced Wednesday its establishment of an integrated “Korea Mission Center.” It will be headed by a veteran operations officer to harness and direct the spy agency’s efforts in addressing the nuclear and ballistic missile threats.

The center will draw on officers from across the CIA and “bring their expertise and creativity to bear against the North Korea target,” an agency statement said.

North Korea’s heightened threat could change Moon’s calculus once in power. He also may need to forge political unity at home after months of upheaval that included his predecessor’s impeachment. That could slow any attempt at rapprochement with the North’s unpredictable leader, Kim Jong Un, at a time of broad international support for sanctions.

The U.S. and North Korea aren’t currently involved in any diplomacy.

But former U.S. officials held two days of informal talks in Oslo, Norway, this week with a Pyongyang delegation led by Choe Son Hui, a senior diplomat for North America. They discussed a range of nuclear, security and bilateral issues, according to a person familiar with the talks. The person wasn’t authorized to publicly discuss the diplomacy and demanded anonymity.

It was the first such “track two” dialogue between the U.S. and North Korea since Trump took office. The U.S. side comprised Suzanne DiMaggio at the New America think tank, former U.N. ambassador Thomas Pickering, retired four-star Adm. William Fallon and former State Department nuclear negotiator Robert Einhorn.

The State Department would only say such meetings “are routinely held on a variety of topics around the world and occur independent of U.S. government involvement.”

Moon, who was a close aide to Roh Moo-hyun, South Korea’s last leader to adopt a “sunshine” policy of diplomatic and economic outreach toward the North, has called for a balance of pressure and engagement.

“I am willing to go anywhere for the peace of the Korean Peninsula,” he said today. “If needed, I will fly immediately to Washington. I will go to Beijing and I will go to Tokyo. If the conditions shape up, I will go to Pyongyang.”

Moon succeeds Park Geun-hye, who was ousted in a corruption scandal. Moon also has questioned the deployment of a U.S. missile defense system the last government rushed into service. China contends the system’s radar ranges into its territory and threatens its security. Trump has called for South Korea to pay the U.S. $1 billion for a system the U.S. has always described as in America’s vital security interests.