Ratas was speaking in the Romanian city of Sibiu, where he was attending a meeting of EU leaders.

The treaty, concerning Estonia's eastern border with the Russian Federation, dates back to 2005 but has been waiting for ratification ever since. Many of the delays come from the Russian side, with the Russian parliament, the Duma, playing a key role here, amid accusations of ''Russophobia'' on the part of Estonia.

The first reading of the bill on ratifying the border treaty passed at the Riigikogu in November 2015.

Mixed messages from coalition

On Monday, EKRE MP Ruuben Kaalep told ERR that the coalition agreement signed by the three parties included a clause which would put bringing the treaty ratification on ice, something which Enn Eesmaa (Centre), chair of the foreign affairs committee, said was news to him.

On Tuesday, foreign minister Urmas Reinsalu (Isamaa) said something slightly different, namely that the coalition agreement does not make any reference to the treaty.

He did however say the matter would be analyzed and proposals put to the government.

EKRE leader Mart Helme then said Thursday that ratification of the border treaty was contingent on Russia recognizing the much-earlier Tartu Peace Treaty of 1920, signed between the newly-independent Estonia and the fledgling Soviet Russian state.

That Russia in effect does not recognize the Tartu treaty in practice is demonstrated by the fact that Estonian territory guaranteed by the peace treaty was never reinstated after the restoration of independence in 1991, principally the town of Petseri and surrounding area (present-day Pechory, in Russia), much of the western shore of Lake Pihkva (Lake Pskov, in Russian), also in the southeast of the country, and a swathe of land east of the Narva River, including the town of Jaanilinn (present-day Russian city of Ivangorod).

Helme did at the same time liken the loss of Petseri to the 2014 annexation of the Crimea by the Russian Federation.

''I find it very difficult to get the border treaty ratified in such a way that there are no changes to the regulation of the treaty of Tartu, and to bilateral relations,'' Helme, who was standing in for the prime minister's absence, said at the government press conference on Thursday.

Helme also drew a parallel with the ''lost'' territory under Russian control – about 5.2 percent of the country's pre-war land area – with the 2008 war in Georgia and more recent fighting in the east of Ukraine, which both led to Russian or pro-Russian separatist forces compromising the territories of those countries.

Can progress if Russians want it to

Speaking on Thursday afternoon, Ratas said in reference to his coalition partners' assessments, Estonia has to exercise some realpolitik.

"We are now going back into our history and into this preamble, which at one point had actually made it impossible for the border agreement to go ahead. We must, of course, take into consideration the aspects of the Treaty of Tartu, but we must also take into account the real situation we live in in 2019," he said.

''The border agreement can only go ahead if both countries want it to. Estonia has angled for getting the border agreement ratified over several Riigikogu compositions. Amongst the current coalition members, there are different positions on the border agreement. If this comes to the table, it will be because the Russian Federation wants it too; I believe that Estonia is ready to discuss things,'' he noted.

Of greater significance, Ratas said, is the completion of the eastern border infrastructure, and ongoing project likely to cost tens of millions of euros over the next few years.

''My opinion is that when talking about what we can control, it is more important that we focus on constructing the border infrastructure at the moment. This is in fact being conducted on a tripartite basis [ie. where the borders of the Russian Federation, Latvia and Estonia converge, in the far south-east of the country-ed.], proceeding in a northerly direction,'' he added.