Syrian Vice President Abdul Halim Khaddam ended two days of high-profile talks here today amid indications that the Soviet Union is planning to upgrade its arms shipments to Syria and Libya, two close allies in the Arab world.

Libya's Maj. Abdul Salaam Jalloud, deputy to Libyan leader Col. Muammar Qaddafi, is also visiting the Soviet capital.

During a meeting yesterday, Soviet leader Mikhail Gorbachev and Khaddam discussed "the issues of increasing assistance" to Syria and "strengthening its defense capability," the official Tass news agency reported. The arms issue was broached "in view of the escalating threat from U.S. imperialism and Israel," it said. Sergei Akhromoyev, chief of the Soviet general staff, and his Syrian counterpart took park.

The increased Soviet military aid most likely refers to plans to upgrade air defense systems, western diplomatic sources here said.

During Gorbachev's talks Tuesday with Jalloud, the Soviet leadership also affirmed its readiness to assist Libya in "strengthening defense potential," Tass reported.

Jalloud and Khaddam met with Defense Minister Sergei Sokolov and other senior Kremlin officials, according to diplomatic sources. Soviet television has included shots of the military leaders together with visiting Syrians and Libyans.

The diplomats interpreted the highly publicized visits, coming on the heels of the U.S. air raids on Libya, as Moscow's show of support for its two allies -- and major arms customers.

Libyan leaders pressed not only for replacement of arrangements lost in the U.S. raids in April, but upgraded weaponry, diplomatic sources said.