NATO's secretary-general says he is confident close bonds between Europe and the United States will survive despite current differences over trade and U.S. decisions to withdraw from the Paris climate accord and the Iran nuclear deal.
"Our bond is strong, but some are doubting the strength of that bond. And, yes, we see differences," Jens Stoltenberg told an audience in London.
"It is not written in stone that the transatlantic bond will survive forever, but I believe we will preserve it," he added.
Stoltenberg said that "we may have seen the weakening" of some bonds, but he insisted that "maintaining the transatlantic partnership is in our strategic interests."
His remarks came before a summit of NATO leaders in Brussels in July.
U.S. President Donald Trump, who has consistently criticized alliance allies for what he sees as an insufficient level of defense spending, is expected to attend.
Stoltenberg said he expected Trump to be "very strong" on defense at the summit, including his demand that NATO members honor a commitment to raise defense outlays to 2 percent of national output.
'Unpredictable Security Environment'
The NATO chief said in his speech that it was important to recognize that European states had started to increase their spending.
"It is possible to say we have done a lot, but a lot remains," he said.
Stoltenberg said the world faced "the most unpredictable security environment in a generation" because of the threat of terrorism, proliferation of weapons of mass destruction, cyberattacks, and an aggressive Russian foreign policy.
"We must continue to protect our multilateral institutions like NATO, and we must continue to stand up for the international rules-based order," he said.
Some European officials have expressed concerns that the U.S. administration will not act strongly enough to punish Moscow for perceived misdeeds, including interference in elections and the nerve-agent poisoning of former spy in England, which Britain blames on Russia.
Trump last month shocked allies at a Group of Seven (G7) summit in Canada when he suggested that Russia be allowed back into the group of leading industrial powers. Moscow was expelled after its annexation of Ukraine’s Crimea region in 2014.
Some allies have also expressed concerns over reports that Trump may meet with Russian President Vladimir Putin when he travels to Europe for the NATO summit.
But Stoltenberg said fellow NATO leaders would have no problem with a Trump-Putin summit.
"We are in favor of dialogue with Russia," he said. "We don't want a new cold war. We don't want a new arms race. We don't want to isolate Russia."