By Andrius Sytas

RIGA (Reuters) -Latvia's president expressed confidence NATO would agree to a new higher defence spending target demanded by U.S. President Donald Trump, despite Spanish objections, saying the alliance had little choice given the growing threat from Russia.

Spain on Thursday asked to opt out of the plan to increase members' defence spending to 5% of their gross domestic product, as requested by Trump, a move which could derail next week's NATO summit at the Hague.

Any agreement to raise defence spending needs unanimous approval by the 32 member states.

Latvian President Edgars Rinkevics told Reuters on Friday he understood why countries further from Russia might have difficulties convincing their voters to spend more on defence. But he said the need was pressing.

“I do hope there is the understanding in Madrid that this is a critical time for the Alliance, both when it comes to (increasing) its defence capabilities, but also to the Trans-Atlantic relationship,” he said in an interview in Riga.

“I think that they don't have much of a choice,” he added.

At an estimated 1.28% of GDP, Spain had the lowest proportion of expenditure on defence in the alliance last year, according to NATO estimates.

Latvia and fellow Baltic states Lithuania and Estonia are urgently ramping up their militaries, fearing that their neighbour and former overlord Russia could push on from its 2022 invasion of Ukraine to take more territory.

They spent more than 3% of GDP on defence this year, and have committed to top 5% for the next few years.

"We are saying that we need to spend as soon as possible now in order to avoid a worst-case scenario, spending much more later," Rinkevics said.

"While Russia is stuck in Ukraine, that possibility of a direct military attack is not very high," he said. "But it may change very, very quickly ... if a development in Ukraine leads Russian leadership to believe that NATO is weak, that Ukraine is defeated, that NATO is divided".

(Editing by Andrew Heavens)