SINGAPORE -- The U.S. is "focused" on evacuation operations from Afghanistan, Vice President Kamala Harris said on Monday during her trip to Singapore, as its retreat from the Central Asian country raised questions about the credibility of U.S. commitments.

"Right now, we are singularly focused on evacuating American citizens, Afghans who worked with us and Afghans who are vulnerable, including women and children," Harris said at a joint news conference with Prime Minister Lee Hsien Loong, when asked to assess what went wrong with the withdrawal. "We cannot be in any way distracted from what must be our primary mission right now."

She also said, "The reason I am here is because the United States is a global leader, and we take that role seriously, understanding that we have many interests and priorities around the world." She added that her trip to Southeast Asia -- she will visit Vietnam later this week -- is "a reaffirmation of our commitment" to partnerships with the region.

Lee, for his part, showed understanding of the U.S. withdrawal from Afghanistan, which opened the way for a rapid Taliban takeover of the country. President Joe Biden's "administration inherited an extremely difficult situation," Lee said. He said Singapore would offer an aircraft to support America's evacuation operation.

But he also noted, "Post-Afghanistan in the longer term, what matters is how the U.S. repositions itself in the Asia-Pacific, engages the broader region and continues to fight against terrorism, because that will determine the perceptions of the countries of the U.S. global priorities and of its strategic intentions."

He pointed out that Afghanistan was a pivotal battlefront in the fight against terrorism, from which extremist ideas were exported to Southeast Asia, and said, "We hope Afghanistan does not become an epicenter for terrorism again."

Harris' visit comes amid China's growing presence in the region. The Biden administration has been reestablishing Washington's Asia policy, which had faded under President Donald Trump.

"I reaffirmed in our meeting the United States' commitment to working with our allies and partners around the Indo-Pacific to uphold the rules-based international order and freedom of navigation," Harris told reporters, "including in the South China Sea," where several countries and regions have claims overlapping with those of China.

Harris arrived in Singapore on Sunday on her first official trip to Asia as vice president. She will make a speech Tuesday morning and meet with industry leaders to discuss building resilient supply chains before heading to Vietnam.

Concerning supply chains, Harris noted that the vulnerability of the U.S. network has been highlighted throughout the COVID-19 pandemic. She said supply chains are "critical to ensuring that businesses can source the materials they need and get products to market and enable people to buy these products."