Reactor 4 explodes at the Chernobyl nuclear power station

The USSR began a unilateral moratorium on nuclear explosions, timed to the anniversary of the Hiroshima bombing and initially set through January 1, 1986. The pledge made Kazakhstan’s test-site...

The leaders met for the first time at the Geneva Summit. Their talks began a new phase of direct engagement, but the encounter remained a negotiation between nuclear superpowers whose decisions...

Reagan and Gorbachev issued a joint statement affirming that nuclear war could not be won and must never be fought, while agreeing to continue talks. The declaration mattered as a diplomatic signal...

The Soviet leader proposed eliminating nuclear weapons worldwide by 2000. The plan was a diplomatic initiative by a nuclear superpower and an appeal to reduce the danger its own arsenal helped create.

The congress endorsed perestroika and called for economic acceleration while preserving the party’s leading role. Public promises of renewal confronted entrenched centralized authority and the Union’s...

After radiation alarms in Sweden and reports abroad, Soviet news briefly acknowledged an accident. The delay and lack of detail eroded trust among communities facing exposure and demonstrated the...

In his televised address, Gorbachev discussed the accident after nearly three weeks of limited public disclosure. His speech did not erase the consequences of delayed evacuation and uneven access to...

After years of confinement in Gorky, physicist and dissident Andrei Sakharov was allowed to return to Moscow. His release signaled a change in political climate while leaving many political...

Gorbachev called for democratization within the party and greater competition in elections. The proposals widened public debate but kept reform under party leadership and did not yet establish...

The law promised enterprises more autonomy and introduced new accounting and labor rules. It aimed to improve productivity without ending central planning, and its effects varied across industries and...