Iran's launch site accident.
Military Times reported that satellite imagery of Iran's Imam Khomeini Space Center in the country's Semnan province showed evidence of a large explosion at the launch site. The Planet Labs image released with commentary by the Middlebury Institute of International Studies is dated August 29th, and shows still smouldering "space launch vehicle debris and burn marks." An image from the same source taken on August 9th showed increased activity at the Space Center that appeared to be preparation for the launch of a Nahid-1 satellite. This would have been Iran's third attempt at a launch, the first two having resulted in failure.
Iran publicly acknowledged the explosion, whose cause it ascribed to technical difficulties. On August 30th President Trump tweeted a photo of the accident site with the accompanying message, "The United States of America was not involved in the catastrophic accident during final launch preparations for the Safir SLV Launch at Semnan Launch Site One in Iran. I wish Iran best wishes and good luck in determining what happened at Site One." The Washington Post said that, according to commentary from the Middlebury Institute, the image in the President's tweet looked as if it had been taken by an aircraft as opposed to a satellite. The Institute didn't call out the specific features in the picture that led them to this conclusion, but the sources the Post cited point to the high resolution and apparent angle from which the image was taken as evidence of the possibility that the image was obtained by an overflying aircraft.
On August 16th US Central Command confirmed that Houthi rebels in Yemen had shot down a US MQ-9 Reaper observation drone. The drone was taken down on June 6th by an SA-6 surface-to-air missile. The altitude at which the drone was flying when it was hit indicates to Central Command that the Houthis have improved their air defense capability, and the Command says that they achieved that improvement with Iranian assistance. Military Times sees this and other incidents as indicating the increasing use of drones in the theater as tensions between Iran, the US, and Iran's regional rivals remain high.
Russia's nuclear accident.
An apparently lethal accident in northern Russia on August 8th is thought, the New York Times reported, to have killed at least seven and produced an unknown degree of local contamination. A brief evacuation order was imposed on a nearby village, then quickly rescinded, according to the Navy Times. Russian spokesmen said the accident happened in the White Sea, off the Nenoksa Missile Test Site west of Severodvinsk, where the Russian Federal Nuclear Center had been studying “small-scale sources of energy with the use of fissile materials.” The US confirmed that it had observed evidence of the accident.
Those "small-scale sorces of energy" are thought to be intended for use in a new cruise missile, the 9M730 Burevestnik, which NATO designates the SSC-X-9 Skyfall. Russian President Vladimir Putin announced the Burevestnik's development last year. The Skyfall's nuclear propulsion system would give it essentially unlimited range and sufficient energy for unrestricted maneuver at low altitudes, enabling it to evade US defenses designed for ballistic missile defense. (There are US anti-cruise missile systems, but intercepting a cruise missile at low altitude presents a different and tougher problem, particularly with respect to sensors and target acquisition, than does the challenge of defending against long-range ballistic missiles.)
Nuclear propulsion for cruise missiles has been explored before (the US abandoned one such effort, Project Pluto, in its preliminary design stages early in the Cold War), but it's an extraordinarily hazardous proposition that essentially involves an airborne unshielded reactor, with all the obvious risk of foreseeable contamination and predictable accidents, like the one at Nenoska. Defense One offers a brief history and appreciation of nuclear-powered cruise missiles. That said, however, there's some doubt as to whether the Russian system represents a real capability or an elaborate disinformation campaign.