Speaking at the White House, where President Joe Biden is hosting the leaders of Finland and Sweden following their formal application for NATO membership, Niinisto said his country was already in discussions to address Turkey's concerns and that those conversations would continue in the coming days.
"Finland has always had proud and good bilateral relations to Turkey. As NATO allies, we will commit to Turkey's security, just as Turkey will commit to our security," Niinisto said.
"We take terrorism seriously. We condemn terrorism in all its forms and we are actively engaged in combating it. We are open to discussing all the concerns Turkey may have concerning our membership in an open and constructive manner," he said.
Finland and Sweden say they have been spurred into joining NATO by Russia's invasion of Ukraine, reversing generations of military non-alignment to bring about the biggest shakeup in European security for decades.
Turkey surprised NATO allies last week by objecting to the move, accusing the two countries of harboring Kurdish militants.
Washington has so far played down the Turkish objections, saying it expects the issues to be resolved.
(Reporting by Steve Holland, Jeff Mason and Humeyra Pamuk; Editing by Daniel Wallis)
