The United Nations warned that some donor states could decrease their aid pledges to Syrians, adding that in 2018, the agency had only received quarter the sum it had requested for humanitarian work in Syria. The EU and UN begun Tuesday a two-day conference in Brussels to gather fresh aid pledges for Syria. In 2017, EU diplomats said the gathering pledged 5.6 billion euros in aids to the war-torn country. This year, UN Secretary General for Humanitarian Affairs Mark Lowcock warned there is a lack of funding for the necessary aid projects, which are being fulfilled from less than 23 percent. He said that out of the needed 3.5 billion dollars, only 800 million were available. The UN official also said that resources for work inside Syria and with refugees in neighboring countries were "desperately short.” Separately, Russian sources said that the Russian Army had noticed increased American military activity in Syria, including the presence of US reconnaissance aircrafts overflying above Syria to search for S-300 positions, which Washington believes Moscow had already offered to Damascus. Russias military stated Tuesday that Russian air defenses at Hmeimim airbase in Syria had intercepted and destroyed several unidentified objects targeting the base. "On April 24, the airspace monitoring facilities at Russias Hmeimim airbase detected a group of small-size unidentified airborne targets approaching the base," an airbase spokesperson said in a statement. "All targets were destroyed by air defense means deployed at the base,” he added. Meanwhile, Defense Minister Avigdor Lieberman warned Tuesday that if Syria uses Russian-made air defense missiles against Israel, Israel will strike back. "Whats important to us is that the defensive weapons the Russians are giving Syria wont be used against us," Lieberman told Ynet news. Russia’s daily Kommersant newspaper reported earlier on Monday that Russia might start supplying the anti-aircraft missile systems to Syria in the near future.