The presidents of Georgia, Ukraine, and Azerbaijan, and the prime minister of Moldova, countries that formed the alliance in 2005 along with former member Uzbekistan as a counterbalance to Russia's influence in the region, passed a declaration outlining cooperation in 2008 in energy, transport and measures to tackle "frozen" conflicts.
Continuing the member-states' line toward diversifying energy routes and reducing dependence on Russia, Ukraine's president, Viktor Yushchenko, said Caspian Sea oil should be pumped through pipelines avoiding Russia.
Azerbaijani President Ilkham Aliyev, in turn, reassured that his country had enough crude in its Caspian fields to fill the Odessa-Brody pipeline designed to pump oil from the Caspian to Europe. The pipeline currently transports mainly Russian oil to Ukraine's Black Sea port of Odessa.
At an informal energy summit in Warsaw in mid-May, Poland, Azerbaijan, Georgia, Lithuania and Ukraine endorsed the extension of the Ukrainian-Polish Odessa-Brody pipeline to Poland's Gdansk port and refinery in Plock.
Speaking about simmering conflicts with breakaway regions in Georgia and Moldova - another irritant in their relations with Russia - the leaders said the disputes were being "artificially provoked" and urged for their resolution.
The outspoken Georgian leader, Mikhail Saakashvili, said the south Caucasus state would regain control of South Ossetia, one of two breakaway regions on its territory, in the next few months.
"[South Ossetian President Eduard] Kokoity's tenure is expiring, and we will finally resolve all problems in the next few months, demonstrating to the world how ethnic conflicts should be tackled," Saakashvili said.
The four countries have reportedly been discussing setting up their own peacekeeping forces to eventually replace Russian troops in Georgia's South Ossetia and Abkhazia and Moldova's self-proclaimed republic of Transdnestr.
Russia has refused to withdraw from the post-Soviet conflict zones, arguing this would trigger new bloodshed similar to the local conflicts that broke out after the Soviet Union's breakup in the early 1990s. Russia enjoys support in the breakaway regions, which have on several occasions voiced their desire to integrate into Russia.
At previous summits, the quartet severely criticized Russia for its military presence in the two states, and also slammed the Commonwealth of Independent States (CIS), which comprises former Soviet republics, as inefficient and Russia-dominated.
This year, the GUAM - which enjoys Washington's backing - was attended by the presidents of Lithuania, Poland, Romania, Bulgaria's vice president, a senior Estonian lawmaker, Latvia's economics minister, a senior U.S. State Department official, and officials from China, Japan, the OSCE, UNESCO and other bodies.
But Russian newspaper Kommersant said Tuesday that Moldovan President Vladimir Voronin had missed the summit, as he was visiting Luxemburg and Brussels for meetings with EU and NATO officials. On Friday, he will meet with Russia's Vladimir Putin.
The regional organization - known as GUUAM until May 2005 when Uzbekistan withdrew - will gather for its next summit in the Georgian capital, Tbilisi, June 2008.