Bulgaria expressed concerns Tuesday that it would not be protected by the planned US missile system in Eastern Europe, which has met with heavy opposition by Russia, according to dpa. Bulgaria was being caught "between the missile shield and a growing tension in Russia," Foreign Minister Ivailo Kalfin said in Sofia Tuesday, one day ahead of the G8 meeting attended by US President George W Bush and Russian President Vladimir Putin. The issue of undivisible security within NATO was extremely important for Bulgaria, said Kalfin, adding the question would be discussed when Bush is due to visit the country on June 10 and 11, following the G8 summit in Heiligendamm, Germany. Sofia was also expecting a clear commitment by Washington to abolish visa requirements for Bulgarians visiting the US. Another issue on the agenda was the US support in Bulgaria's attempts to free five Bulgarian nurses sentenced to death in Libya for deliberately infecting 400 children with HIV. The formerly communist country has emerged as one of Washington's closest allies in Southeast Europe. It became a member of what Bush called the "coalition of the willing" in the US-led war on Iraq and also participates in the Nato-led International Security Assistance Force (ISAF) in Afghanistan. In 2006, Sofia had signed an agreement with the US to allow the construction of four US military bases on its territory.