Four Danish F-16 warplanes landed in Estonia on Wednesday, marking the first time NATO planes will be stationed in the ex-Soviet state and Russian neighbour.

The aircraft and a supporting team of 60 people arrived at the Amari air base in the west of the Baltic state at a time when NATO is reinforcing its presence in the region to allay concerns triggered by the Ukraine crisis.

"Your arrival in Estonia and the opening of the Amari base to regular NATO flights increases the security of our region," Estonian Prime Minister Taavi Roivas said at a ceremony.

"But work on the security of Estonia and Europe is far from over. We are working to make our NATO allies' stay in Estonia permanent."

Until now the Western defence alliance's sole Baltic air base was in Siauliai in northern Lithuania, Estonian defence forces spokesman Roland Murof said.

Some 150 US troops also arrived in Estonia on Monday, part of a 600-strong force that Washington sent to Poland and the Baltics to reassure the region.

Britain also sent four Typhoon fighters to Lithuania this week, while Poland contributed four MiG 29s, and France sent four Rafale jets to Poland.

Baltic states Estonia, Latvia and Lithuania spent five decades under Soviet occupation until 1991 before joining NATO and the European Union in 2004.