Showing off tents, lifeboats and other rescue equipment at the Russian-Serbian Humanitarian Centre, co-director Viacheslav Vlasenko laughs at Western suspicions that his workplace is a front for a spy operation.
"We are very open here," the cordial 70-year-old Russian told AFP at the base in the strategically-located town of Nis in southern Serbia -- not far from Kosovo with a large NATO-led peacekeeping force.
Vlasenko listed all the crises in the Balkans that he says his team has helped to tackle, including forest fires, major floods and the huge influx of migrants across the region in 2015.
"We are not politicians, we are fulfilling our mission, I hope in a good way," he said.
The centre was set up on the basis of a 2012 agreement between Russia and Serbia, with the stated aim of providing humanitarian assistance and training for emergencies in the Balkans.
But since its inception, the project has sparked concerns among Western officials and analysts that Moscow has underhand intentions of using it for espionage or as a so-called lily pad -- an outwardly low-key advance base for military intervention in the region.
Russia's as-yet-ungranted request for the centre and its staff to have diplomatic immunity has only heightened the suspicions, although Vlasenko insisted that the request had been made simply to reduce taxes.
"You have seen now each corner of our centre," he said after giving a tour of the building. "Is it possible to use it for military (purposes)? It's nonsense."
Russia is often perceived as a big brother figure to Serbia, a fellow Slavic and Orthodox Christian nation. Moscow backs Belgrade, for example, in refusing to recognise the independence of Kosovo, a former Serbian province.
As Serbia and other Balkan countries pursue European Union membership, however, Russia has stepped up efforts to boost its regional influence.
- Balkan 'chessboard' -
Last month Montenegro joined NATO -- to Moscow's anger -- effectively completing the Western alliance's control of the Adriatic coast. Albania and Croatia have been members since 2009.
The development came several months after an alleged attempt to overthrow the government in Podgorica, a murky affair in which Montenegrin prosecutors said "Russian state bodies" were involved with the aim of preventing NATO accession.
Moscow denies the accusations.
The EU's foreign policy chief Federica Mogherini warned in March, when asked about Russia's role in the region, that the Balkans "can easily become one of the chessboards where the big power game can be played".
There is little on display to suggest dodgy activities at the quiet centre in Nis, where a couple of cheerful men in uniform -- on three-month rotations from Russia's Ministry of Emergency Situations (EMERCOM) -- tick off checklists of rescue equipment.
Screens in a small crisis operations room show satellite images that can pick up fires and project flood patterns.
The centre, which cost more than $40 million (35 million euros) to set up, currently has five Russian and 15 Serbian staff members, including interpreters and technicians, Vlasenko said.
In a major emergency EMERCOM sends in relief teams and aircraft, he added.
- 'Nefarious activities' -
At a US Senate hearing last month on "Strengthening Democracy and Countering Malign Foreign Influence" in southeast Europe, US Deputy Assistant Secretary of State Hoyt Brian Yee expressed concerns over "this so-called humanitarian centre".
He feared "not so much what it is now, but what it might become if it receives what Russia has been asking from Serbia, which is some kind of special status to protect it, diplomatic status or other immunity".
Yee noted the centre's proximity to the border with Kosovo.
"If (Serbia) allows Russia to create some kind of special centre for espionage or other nefarious activities it will lose control over part of its territory," the senior US official said.
Spying plans or not, the project is aiding Russia's drive to win hearts and minds in the region. Certificates of appreciation for its aid in times of crisis line the entrance foyer.
The centre has also helped to clear explosives remaining from NATO's bombing of Serbia in 1999 during the Kosovo war, an episode that still fuels deep scepticism towards NATO among Serbs.
Opinion polls in Serbia regularly show more favourable views of Russia than the EU -- even though European funding far outweighs that from Moscow.
And Belgrade refused to join Europe in imposing sanctions on Russia over the Ukraine crisis.
Serbian authorities have taken a cautious wait-and-see attitude towards granting the centre immunity -- some have spoken in favour, but the country's strongman, President Aleksandar Vucic, has so far resisted it.
The controversy is symbolic of the "real mistrust" between Russia and the West, according to Aleksandra Joksimovic, head of the Centre for Foreign Policy, a Belgrade-based non-governmental organisation.
"I think Serbia is closely watching how not to cross red lines on one side or the other," she said.
© 2017 AFP