Vice President Mike Pence has drawn a line in the sand on tariffs, saying China must meet President Donald Trump's terms in order to end the trade war.

Speaking at the APEC summit for world leaders in Port Moresby, Papua New Guinea on Saturday, Pence traded barbs with Chinese President Xi Jinping in a pair of dueling speeches.

'The United States, though, will not change course until China changes its ways,' Pence said, accusing Beijing of intellectual property theft, unprecedented subsidies for state businesses and 'tremendous' barriers to foreign companies entering its giant market.

It came as, back in the U.S., Trump blasted an anonymously sourced report claiming he questions Pence's loyalty, telling reporters on Saturday morning: 'No, I don't question his loyalty at all. He's 100% loyal. I doubt they had any sources. A typical New York Times phony story.'

Vice President Mike Pence (top) looks at China's President Xi Jinping (bottom) as they prepare for a 'family' photograph during the APEC summit on Saturday in Papua New Guinea

Pence vowed in a speech that the US would not change course on tariffs until China remedied its own trade barriers and addressed rampant intellectual property theft

Trump conveyed similar sentiments in a pair of tweets later on Saturday.

Pence said in his speech there would be no letup in Trump's policy of combating China's mercantilist trade policy and intellectual property theft that has erupted into a tit-for-tat tariff war between the two world powers this year.

The U.S. has imposed additional tariffs on $250 billion of Chinese goods and China has retaliated. Pence reiterated Trump administration threats to more than double the penalties.

Pence announced the U.S. would be involved in ally Australia's plan to develop a naval base in Papua New Guinea, where the summit is being held. China has been intensely wooing Papua New Guinea and other Pacific island nations with aid and loans for infrastructure.

'Our vision for a free and open Indo-Pacific will prevail,' Pence said.

The vice president harshly criticized China's global infrastructure drive, known as the 'Belt and Road Initiative,' calling many of the projects low quality that also saddle developing countries with loans they can't afford.

The U.S., a democracy, is a better partner than authoritarian China, he said.

'Know that the United States offers a better option. We don't drown our partners in a sea of debt, we don't coerce, compromise your independence,' Pence said. 'We do not offer constricting belt or a one-way road. When you partner with us, we partner with you and we all prosper.'

Chinese President Xi Jinping (right) and Russia's Prime Minister Dmitry Medvedev arrive for a family photo during the APEC Summit in Port Moresby on Saturday

In his own speech, Xi fired back at criticism, saying 'Mankind has once again reached a crossroads. Which direction should we choose? Cooperation or confrontation?'

Xi, who spoke before Pence, anticipated many of the U.S. criticisms in his speech. He said countries are facing a choice of cooperation or confrontation as protectionism and unilateralism spreads.

Xi expressed support for the global free trading system that has underpinned his country's rise over the past quarter century to the world's second-biggest economy after the U.S.

'The rules made should not be followed or bent as one sees fit and they should not be applied with double standards for selfish agendas,' Xi said.

'Mankind has once again reached a crossroads,' he said. 'Which direction should we choose? Cooperation or confrontation? Openness or closing doors. Win-win progress or a zero sum game?'

Responding to a chorus of criticism of China's international infrastructure drive, Xi said it was not a trap or power grab.

'It is not designed to serve any hidden geopolitical agenda, it is not targeted against anyone and it does not exclude anyone,' Xi said. 'It is not an exclusive club that is closed to non-members, nor is it a trap as some people have labeled it.'

A security officer checks a performer in a traditional dress at a security screening at Jacksons International Airport in Port Moresby, Papua New Guinea, ahead of Pence's arrival Saturday

Pence arrives at Jacksons International Airport ahead of the APEC summit in Port Moresby, Papua New Guinea on Saturday

Dancers in traditional dress perform as Pence arrives in Port Moresby, Papua New Guinea

Well-wishers hold an American flag as Pence's motorcade travels through Port Moresby

Leaders of 21 Pacific Rim countries and territories that make up 60 percent of the world economy are meeting in Port Moresby, the capital of Papua New Guinea, for an annual Asia-Pacific Economic Cooperation summit.

They are struggling to reach agreement on a joint declaration, particularly whether to push for changes to the World Trade Organization, which sets the rules for trade and can penalize nations that breach them.

WTO member nations have been unable to reach agreement on further freeing up trade for years and the organization is in danger of atrophy.

Two thirds of its members claim 'developing nation' status that allows them to take advantage of benefits and exemptions to obligations not granted to advanced economies, according to the Center for Strategic and International Studies. The U.S., meanwhile, believes the WTO's arbitration body has made decisions beyond its mandate.

In a last-minute reversal, Pence said on on Saturday that he will spend the night in Papua New Guinea where he is attending a regional summit, changing plans to fly in and out of Australia which had led to complaints of a lack of commitment.

Pence had originally been due to shuttle to the APEC talks from the northern Australian city of Cairns rather than stay overnight in Port Moresby, which is hosting the gathering for the first time.

Papuans gather at the roadside to welcome China's President Xi Jinping in Port Moresby on Friday. The sign says 'Welcome President Xi! Thank you for building our school and road'

Locals wave as Chinese President Xi Jinping's motorcade passes in Port Moresby on Friday

China's President Xi Jinping inspects the guard of honor at Parliament House in Port Moresby on Friday ahead of the Asia-Pacific Economic Cooperation (APEC) Summit

But the White House confirmed that Pence would instead spend the night in the Pacific island nation, shrugging off its reputation for violence and petty crime.

'Staying in PNG is better for the schedule and the office was able to make it work, from a logistical and security standpoint,' a senior administration official told AFP.

The port city is effectively on lockdown with a heavy police presence and warships from the US, Australia and New Zealand patrolling offshore.

Due to security and a dearth of hotel rooms, most journalists and delegates are billetted on two hulking cruise ships moored in the harbour with ultra-tight security access.

Although the threat posed by terrorism in Papua New Guinea is considered minimal, the Melanesian country has developed a reputation for lawlessness.

Feared street gangs known as 'raskols' have made carjackings common and the country has among the highest rates of rape and domestic violence in the world.

Performers in traditional costumes and headdress welcome delegates and ministers to the international convention centre for the 30th Asia-Pacific Economic Cooperation (APEC)

Children play beside the bay at Port Moresby, Papua New Guinea on Thursday. Feared street gangs known as 'raskols' have made carjackings common in the lawless city

Residents are seen in the village of Hanuabada, one of only two remaining stilt villages in Port Moresby on Thursday

Pence's decision to stay in Papua New Guinea now puts him in the same boat as China's President Xi Jinping, whose delegation has locked down the Stanley Hotel where Chinese lanterns abound and a pagoda has been constructed in his honour.

Some of the leaders are thought to be staying at the Airways hotel - 'one of the world's most unique airport hotels', according to its website.

Hotel guests describe security arrangements at the Airways as 'immense' even without the APEC summit, complete with shotgun-toting guards at the gates.

'But that is nothing compared with what we see now,' a resident said on Saturday, citing snipers on the roof, parts of the hotel sealed off, road blocks and special clearance required for cars.

Many delegates and journalists at APEC are staying aboard cruise ships such as the Pacific Jewels (above) due to security concerns at the summit

The US Navy's USS Green Bay (LPD 20) patrols the harbor near the Asia-Pacific Economic Cooperation (APEC) Haus ahead of APEC summit in Port Moresby, Papua New Guinea

APEC is facing questions about its future. Malaysia's 93-year-old Prime Minister Mahathir Mohamad said it will become irrelevant if developing nations continue to be left behind by globalization and free trade.

China's territorial claims to most of the South China Sea that borders Southeast Asian nations were also a target in Pence's speech.

China has demanded the U.S. stop deploying ships and military aircraft close to its man-made islands in the disputed waters after American and Chinese ships nearly collided near a contested reef in September. But Pence stressed Saturday that the U.S. won't back off.

'We will continue to fly and sail wherever international law allows and our national interest demands,' he said. 'Harassment will only strengthen our resolve. We will not change course.'

Washington will continue to support efforts by Southeast Asian nations to negotiate a legally binding 'code of conduct' with China 'that respects the rights of all nations, including the freedom of navigation in the South China Sea,' Pence said.