BRUSSELS - NATO allies may decide to aim to spend more on defence than their current target of 2% of national output when they meet for their next summit in Vilnius in July 2023, the chief of the alliance said on Monday.

"I expect that, in one way or another, even though perhaps the 2% will be kept, it will be kept more as a kind of floor than a ceiling for defence spending," NATO Secretary-General Jens Stoltenberg said during a visit to Spain.

"These are negotiations that will go on, but I'm absolutely confident that the ambitions will be increased in one way or another - because everyone now sees the need for investing more," he added.

In response to Russia's annexation of Ukraine's Crimea peninsula in 2014, NATO leaders pledged to reverse the trend of declining defence budgets, with allies agreeing to spend at least 2% of economic output on defence from 2024.

Since Russia's invasion of Ukraine in February this year, many allies have increased their military spending.

"I cannot tell you exactly what our allies will agree when it comes to formulating the pledge for defence spending for the next decade or so... but I expect that it'll be an even stronger commitment to increasing defence spending," Stoltenberg said.

(Reporting by Sabine Siebold and Marine Strauss Editing by Peter Graff)