The United States and Bulgaria have signed an agreement that will allow US troops to use three military bases in Bulgaria.
US troops could be deployed to trouble spots from Bulgarian bases
The BBC's South-East Europe analyst Gabriel Partos examines the details of the agreement.
Ever since the United States announced two years ago a big shake-up in its military presence in Europe, Bulgaria has been among the countries lobbying most eagerly for the stationing of US troops on its territory.
Some 70,000 US troops are being withdrawn from their traditional bases in Western Europe - the bulk of them from Germany - and they are being redeployed mostly at home or in and around trouble spots, such as Iraq and Afghanistan.
But a relatively small number, perhaps about 2,500, will start using Bulgarian military facilities next year. The agreement was signed by US Secretary of State Condoleezza Rice and her Bulgarian opposite number, Ivaylo Kalfin, on the fringes of an informal gathering of Nato foreign ministers in Sofia on Friday.
The deal allows US forces to be stationed at Bezmer air base and the Novo Selo army training range near the border with Turkey, and at Graf Ignatievo airfield in central Bulgaria.
Crucially, the deal allows Washington to deploy troops from their Bulgarian bases for missions in third countries in consultation with - but if need be, without the specific permission of - the Sofia government.
Facilitating the speedy deployment of US troops in conflict zones in the Middle East and beyond is likely to be the main function of the three new US military bases in Bulgaria in times of crisis. The rest of the time they will serve as training centres for troops that will be rotated at frequent intervals, as well as providing storage facilities to help resupply troops deployed further afield.
The three bases will be used jointly with Bulgarian forces. This form of co-operation is viewed by Sofia as one of the advantages of the deal.
"We expect this agreement for joint training and joint use of existing military facilities in Bulgaria together with the American armed forces to increase the capacities of the Bulgarian army," says Bulgarian foreign ministry spokesman Dimitar Tsanchev.
The US bases in Bulgaria, like their counterparts in Romania, will be very different from the traditional US military facilities in Germany and elsewhere in Europe.
Instead of stationing large forces on a long-term basis to face a potential threat - as in the case of the Soviet Union during the days of the Cold War - these bases will host small, streamlined and mobile units that can quickly be moved elsewhere to deal with a crisis.
Apart from the Middle East, the geographic advantages of the bases in Bulgaria and Romania allow them to be used for potential intervention - whether of a military, peacekeeping or humanitarian nature - in the Caucasus, the Black Sea and the Balkans.
But because of their relatively small size, the bases in Bulgaria are unlikely to generate the kind of economic benefits that the traditional, larger bases have done in terms of creating employment for local civilians and contractors.
However, Dimitar Tsanchev expects a real economic advantage, albeit of a less direct kind.
"We think that in the economy, the joint use of these military facilities will lead to an increase in the confidence in our country on behalf of investors and improve the general investment climate in our country," he said.
"The assessments of international business circles regarding Bulgaria as a secure, stable and predictable partner are also a premise to realise a lot of infrastructure projects."
The new US bases in Bulgaria and Romania will follow others that have been established - and in some cases already closed down - in formerly communist-ruled countries.
The first of these was in Taszar in Hungary which was used as a supply facility for US peacekeepers that were being based in Bosnia-Hercegovina at Tuzla following the Dayton peace accords of 1995.
With the replacement of Nato by the EU in command of the peacekeeping presence in Bosnia in 2004, Taszar and Tuzla were vacated by the Americans - though a small US detachment remains in Bosnia to help the search for war crimes suspects still at large.
But Camp Bondsteel, the base for US peacekeepers in Kosovo, is still going strong.
Meanwhile, US bases have also been established in two former Soviet republics in Central Asia, primarily to serve as bridgeheads for military operations in Afghanistan.
The US base at Karshi-Khanabad in Uzbekistan was closed down last year after the Uzbek authorities objected to US support for an inquiry into the violent suppression of anti-government protests in the town Andijan.
In Kyrgyzstan, the authorities have recently warned that they may ask the US to leave its air base near the capital, Bishkek, unless there is a big increase in the fee Washington is paying for its use.
There is unlikely to be such a demand coming from Bulgaria or Romania in the next few years. Both are Nato members, keen to demonstrate their reliability within the alliance. In any case, the agreements with the US are to be in force for a period of 10 years, after which they can be renewed.