NATO foreign ministers have marked the 70th anniversary of the transatlantic military alliance in Washington amid disagreements over security and costs.
US Secretary of State Mike Pompeo urged allies at the start of a meeting of North Atlantic Treaty Organisation foreign ministers to adapt to confront a wide variety of emerging threats, including from Russia and China.
"We must adapt our alliance to confront emerging threats ... whether that's Russian aggression, uncontrolled migration, cyber attacks, threats to energy security, Chinese strategic competition, including technology and 5G, and many other issues," Pompeo said.
In a 2018 strategy document, the US military put countering China and Russia at the heart of a new national defence strategy.
The meeting's first session focused on ways to deter Russia, including in the Black Sea where it seized three Ukrainian naval vessels last year.
NATO chief Jens Stoltenberg called on Moscow to release the ships and their crews.
He said Russia's breach of the 1987 Intermediate-range Nuclear Forces Treaty was part of a "pattern of destabilising behaviour".
Washington has said it will withdraw from the treaty this (northern) summer unless Moscow ends its alleged violations of the pact, which rid Europe of land-based nuclear missiles.
"We will not mirror what Russia is doing," said Stoltenberg. "We will be measured and co-ordinated, and we have no intention of deploying ground-launched nuclear missiles in Europe."
In his remarks, Pompeo said NATO should also confront increased cyber warfare, including from China.
Washington has warned it will not partner with countries that adopt China's Huawei Technologies systems, but has been at odds on the issue with the European Union, which has shunned US calls to ban the company across the bloc. The bulk of NATO members are EU countries.
Huawei is under scrutiny from Western intelligence agencies for its perceived ties to China's government and the possibility its equipment could be used for espionage.
Huawei has repeatedly denied engaging in intelligence work for any government.
The US has also been at odds with European countries over the failure of many of them to meet NATO defence spending guidelines of 2 per cent of GDP.
Stoltenberg told reporters that NATO allies should commit to increased defence spending to improve burden-sharing in NATO.
"All NATO allies made a pledge to invest more in defence to improve burden sharing in our alliance, and I expect all allies, including Germany, of course, to make good on the pledge we made together," the NATO secretary general said.
US President Donald Trump has called on NATO countries to pay even more than 2 per cent of their gross domestic product for defence. He told NATO leaders last year to increase defence spending to 4 per cent of GDP. He said the US pays 4.3 per cent of its GDP to NATO.
"We didn't make this pledge to please the United States. We made it because we live in a more unpredictable and uncertain world," Stoltenberg said.
The NATO chief said disagreement between NATO members Turkey and the US over Turkey's plan to buy S-400 missile defence systems from Russia was not part of the formal agenda of the Washington meeting, but would be discussed on the margins.
The US has halted delivery of equipment related to its advanced F-35 fighter jets to Turkey over its S-400 plans.
The US says Turkey's purchase of the Russian air defence system would compromise the security of F-35 aircraft.
