Raimonds Vejonis officially started his duty on Wednesday as Latvian president after a symbolic handover ceremony with the former president Andris Berzins in the House of the Blackheads in Riga.
As the first Green president among EU countries, Vejonis, 49, swore to prioritise the national security of Latvia, referring to Russia as a potential threat.
He spoke to the parliament saying “today, many in Europe have woken up from a deep slumber. Our neighbouring country's aggression in Ukraine proves that military and technological security still matters. And we must affirm that not only in words, but also in actions."
Green Party member and former Latvian Defence Minister Vejonis was elected as the country’s new president at the beginning of June to replace Andris Berzins.
Vejonis is known for his support of NATO and his stand against pro-Russian separatist rebels fighting in eastern Ukraine.
Before taking on the role of defence minister in 2014, Raimonds Vejonis served as the environment minister twice between 2003 and 2011.
Meanwhile, the Latvian parliament appointed Green party parliament member Raimonds Bergmanis as defence minister on Wednesday when the post was vacated by Vejonis, the new president elect.
The Latvian Green Party (LZP) was founded in 1990 as a member of European Green Party, but unlike most Green parties around the world that generally stand in the centre-left, the Latvian Green Party is a centre-right party.
The Latvian president also maintains the role of commander in chief of the military and has the right to nominate the prime minister as well as propose or veto legislation.
The Baltic NATO and eurozone member country has placed great importance on national security after the Russian annexation of Crimea last year.
Tensions with Russia
Countries in the Baltic region have particularly been on alert since Russia annexed the Crimean peninsula from Ukraine after Ukraine’s former pro-Russian president Viktor Yanukovych fled a pro-EU uprising last year.
Russia is also accused of supporting separatist rebels in eastern Ukraine who have been fighting for the independence of the self-proclaimed Donetsk People’s Republic since Yanukovych’s demise, leading to heightened tensions between Russia and Western allies in eastern Europe, Scandinavia and the Baltics.
Latvia's Foreign Minister Edgars Rinkevics previously said that a war of words between Russia and the West could degenerate into something worse, with "devastating" consequences.
Both Russia and NATO have increased their military exercises in the Baltic region since the Ukraine crisis put the two military giants at odds with one another.
The Baltic states have also been increasing their defence budget this year in comparison to last year.
According to a report released by Swedish think-tank SIPRI, Latvia increased its weapons budget by 15 percent.
In March, the US sent 750 military tanks, helicopters, and other heavy equipment, along with nearly 3,000 soldiers to the region to participate in a three-month training exercise in a show of strength against Russia.
The sending of heavy military equipment by the US to Latvia was condemned by Russian Foreign Minister Sergey Lavrov, who said the move was not helping the restoration of trust between Russia and NATO.
NATO is bound by a 1997 agreement with Russia which prevents it from stationing permanent troops in Latvia as well as Lithuania and Estonia.