MADRID, June 9, 1988 (UPI) - NATO Secretary-General Lord Carrington opened the spring meeting of the 16 allied foreign ministers today with the warning that the Soviet ''military machine'' is still a threat.

MOSCOW, June 23, 1988 (UPI) - The Communist Party conference that Mikhail Gorbachev convenes this week is a monument both to the sweeping changes initiated during his three years in power and the immensity of the obstacles still in the way of ultimate success.

MOSCOW, June 28, 1988 (UPI) - The following are quotes on key subjects covered by Soviet leader Mikhail Gorbachev in his address to the 19th Communist Party Conference that opened Tuesday:--The slow pace of perestroika (restructuring):

MOSCOW, June 28, 1988 (UPI) -- Soviet leader Mikhail Gorbachev made it clear in his speech Tuesday to the opening session of the 19th Communist Party conference that there are limits to his policies of political and economic reform and the Soviet Union's Facing criticism from conservatives, he said the limit had been reached in two areas: nationalist unrest in the three Baltic states plus the Asian republics and street protests from dissident groups in Moscow.

MOSCOW, June 28, 1988 (UPI) -- Mikhail Gorbachev, warning that political reform is vital to the future of the Soviet Union, called Tuesday for a fundamental overhaul of the Soviet system of government to curb the all-encompassing power of the Communist Party.

MOSCOW, June 28, 1988 (UPI) - Soviet leader Mikhail Gorbachev extended his criticism of the previous leadership to foreign policy today, condemning the ''narrow circle'' that had shaped the country's international relations.

MOSCOW, June 29, 1988 (UPI) - Soviet leader Mikhail Gorbachev, joining the debate at the historic Communist Party conference, warned Wednesday there was a conservative conspiracy to suppress discussion of his economic and social reforms.

MOSCOW, June 29, 1988 (UPI) - An extraordinary Communist Party conference moved behind closed Kremlin doors today for a second day of debate on Mikhail Gorbachev's proposal to overhaul the Soviet political structure by introducing a presidential system with a strengthened legislature.