President Park Geun-hye returned home Sunday from a visit to Washington after she and U.S. President Barack Obama reaffirmed their countries' alliance and their commitment to resolve the North Korean nuclear standoff.

The two leaders pressed North Korea to give up its nuclear weapons program and called their alliance "a linchpin of peace and security" not just on the Korean Peninsula but across the region."

The summit dispelled worries among some critics that Seoul may be tilted toward China as Park attended the massive military parade in Beijing last month, widely seen as a show of force amid the growing rivalry between the U.S. and China.

Obama said that Washington is prepared to engage North Korea as it did Iran and Cuba, but he made it clear Pyongyang must give up its nuclear weapons program.

Iran has reached a deal with the U.S. and five world powers on curbing its nuclear capabilities in return for lifting sanctions.

Cuba, one of a handful of governments with friendly ties with North Korea, has recently restored diplomatic relations with the U.S.

"As my administration has shown with Iran and with Cuba, we are also prepared to engage nations with which we have had troubled histories, but Pyongyang needs to understand it will not achieve the economic development it seeks so long as it clings to nuclear weapons," Obama said in a joint news conference with Park.

Park's four-day visit, which marks her second trip to Washington as president after the first visit in 2013, was also full of gestures and remarks underlining the significance of relations with the U.S., South Korea's No. 1 ally, which fought alongside the country during the 1950-53 Korean War.

"I came here to convey South Koreans' mind that (we) will not forget those who helped us when we were in trouble," Park told a group of surviving veterans and family members of those who served in the Korean War after laying a wreath at the Korean War Veterans Memorial.

In a gala dinner Wednesday, Park said South Korea is a "reliable partner" and the Korea-U.S. alliance is the linchpin of the United States' "rebalance to Asia" policy. Park also said that South Korea will remain an "eternal friend" of the U.S.

The U.S. also went to great lengths to demonstrate the firmness of the relationship.

When Park visited the Pentagon on Thursday, the Defense Department held a "full honor parade" for the first time since Defense Secretary Ash Carter took office in February, a move that showed its respect for the leader of one of the strongest U.S. allies. (Yonhap)