US President Barack Obama opened a meeting with his Chinese counterpart Xi Jinping with a promise of candid discussion over Beijing's alleged military buildup in the South China Sea.
"We will have candid exchanges about areas where we have differences, issues like human rights, cyber and maritime issues," Obama said as he sat across the conference table from his Chinese counterpart.
US officials have expressed concern that China's actions in the South China Sea are not consistent with Xi's pledge at the White House last year not to pursue militarization of the hotly contested and strategically vital waterway.
China claims virtually all the South China Sea despite conflicting claims by Brunei, Malaysia, Vietnam, Taiwan and the Philippines, and has built up artificial islands in the area in recent months, including some with airstrips.
"We do continue to be concerned about militarization in the South China Sea," said senior Obama foreign policy aide Ben Rhodes ahead of the meeting with Xi.
"We certainly have seen developments, reports that are not consistent with commitments to avoid and to non-militarize the South China Sea."
"This will be certainly an important topic of conversation between the two presidents."
Washington has since October carried out two high-profile "freedom of navigation" operations in which it sailed warships within 12 nautical miles of islets claimed by China.
Xi spoke of the need to avoid misunderstandings and big disruptions in the "major power relations" between the two countries.
But state-run news agency Xinhua cited the Chinese leader as saying that "China will not accept any behavior under the disguise of freedom of navigation that violates its sovereignty and damages its security interests."
Obama and Xi also discussed pressure on North Korea, which in January detonated a nuclear device and launched a long- range rocket a month later, prompting UN sanctions backed by both Beijing and Washington.
"Of great importance to both of us is North Korea's pursuit of nuclear weapons, which threatens the security and stability of the region," said Obama.
"President Xi and I are both committed to the denuclearisation of the Korean peninsula and the full implementation of UN sanctions."
"We are going to discuss how we can discourage actions like nuclear missile tests that escalate tensions and violate international obligations.
