European Union foreign policy chief Josep Borrell and Ukrainian Foreign Minister Dmytro Kuleba visit the line of contact in Luhansk, Ukraine.Anadolu Agency | Anadolu Agency | Getty ImagesThe United States and Russia are having key talks next week and the EU’s top diplomat is disappointed that the bloc will not be around the table as well.A potential Russian invasion of Ukraine is a top concern for many leaders, given multiple reports of heightened military activity close to the border. In a bid to ease these tensions, top U.S. and Russian officials will be gathering in Geneva, Switzerland on Monday. This meeting will precede wider talks between Russia and members of the North Atlantic Treaty Organization (NATO) on Wednesday.However, the EU — the political and economic group of 27 nations — will not be present as a whole despite several of its members bordering with Russia.”There is no security in Europe without the security of Ukraine. And it is clear that any discussion on European security must include European Union and Ukraine,” Josep Borrell, the EU’s high representative in charge of foreign affairs, said at a press conference on Wednesday.”Any discussion about Ukraine must involve Ukraine first of all. And the talk about security in Europe cannot be done without not only the consultations, but the participation of the Europeans,” Borrell said in Ukraine, where he visited the eastern part of the nation where low-scale military skirmishes between Ukrainian troops and pro-Russian forces have been going on for several years.This marked the first time that the EU’s top diplomat visited the conflict-hit region.However, an analyst at consultancy firm Teneo, said that the exclusion of the EU from the talks is not surprising.”The sidelining of the EU from the upcoming talks is hardly surprising, given that NATO, and particularly the U.S., serves as the main guarantor of security in CEE (Central and Eastern Europe),” Andrius Tursa, said Wednesday in a note.In fact, the EU as a whole does not have a strong defense capacity — it relies mostly on NATO, and to some extent on the U.S., when it comes to security.But, regardless of its security capacities, there’s a lot at stake for the EU in upcoming talks with Russia, including on the energy front.The majority of natural gas going into Europe already comes from Russia. In 2020, this represented about 43% of the total gas imports to the bloc, according to Eurostat. And a key pipeline between Russia and Germany, Nord Stream 2, is hanging in the balance amid the ongoing tensions with the Kremlin — this is a problem for Russia because it could be making more money from gas exports, and for the EU too because it could help containing some of the price increases registered in the last months.Wolfgang Ischinger, former German ambassador to the U.S., told CNBC earlier this week that Nord Stream 2 is something that the EU can use to pressure Moscow.”I think the pipeline represents a major item of leverage for us, if we handle it smartly,” Ischinger, now chairman of the Munich Security Conference, told CNBC’s Hadley Gamble.An icy relationshipBorrell’s aim to be included in the talks with Russia comes almost a year after a “humiliating” trip to Russia.The EU’s top diplomat visited Moscow last February to voice the bloc’s opposition against the arrest of Russian opposition politician Alexei Navalny. During the trip, Borrell was heavily criticized after failing to rebuff comments from his Russian counterpart that the EU was an “unreliable partner.”This took the EU-Russian relationship to a new low, according to political analysts.However, concerns about a potential Russian invasion of Ukraine are complicating their relationship further.”The conflict on the borders is on the verge of getting deeper and tensions have been building up with respect to the European security as a whole,” Borrell said Wednesday.It is estimated that about 100,000 Russian troops have been deployed to the country’s border with Ukraine. Both countries have been at war since 2014 — the year when Moscow annexed Crimea.The Kremlin, for its part, has denied any plans to invade Ukraine.However, Russia has demanded that NATO and the U.S. decrease their presence in eastern Europe and do not allow Ukraine to become a member of the military alliance.One of the founding principles of NATO is that an attack against one of them is considered an attack against all.