President Sauli Niinistö of Finland says his country is open to discussing any concerns Turkey may have in regards to their application to join NATO in an "open and constructive manner." Niinistö comments came Thursday during a joint press conference with US President Joe Biden and Prime Minister Magdalena Andersson of Sweden at the White House. He added: “We take terrorism seriously. We condemn terrorism in all its forms and we are actively engaged in combating it.” Sweden's Andersson said her nation was also reaching out to Turkey, and other NATO nations, “to sort out any issues.” Applications were submitted this week from once-neutral Sweden and Finland to join the North Atlantic Treaty Organization in response to Russia's invasion of Ukraine. Russian President Vladimir Putin has demanded that the alliance stop expanding toward Russia’s borders, and several NATO allies, led by the United States and Britain, have signaled that they stand ready to provide security support to Finland and Sweden should the Kremlin try to provoke or destabilize them during the time it takes to become full members. Putin cited Ukraine's aspirations to join NATO as one reason for his invasion of the country. The leaders' optimism for Sweden and Finland's applications was set against lingering opposition from Turkey, whose President Recep Tayyip Erdogan said in a Thursday video that he remains opposed. Each of NATO's 30 member countries has the power to veto a membership bid. Erdogan has said Turkey’s objection stems from grievances with Sweden’s - and to a lesser degree with Finland’s - perceived support of the banned Kurdistan Workers’ Party, or PKK, and an armed group in Syria that Turkey sees as an extension of the PKK. The conflict with the PKK has killed tens of thousands of people since 1984. Turkey also accuses Sweden and Finland of harboring the followers of Fethullah Gulen, a U.S.-based Muslim cleric whom the Turkish government blames for 2016 military coup attempt. The objections echo longtime Turkish complaints over even more substantial U.S. support for Kurds, as well as Gulen's presence in America.