However, Kerry expressed "strong concern" about pro-Russian separatists' downing of a Ukrainian transport plane while it attempted to land at the Luhansk airport in the early morning hours of June 14, killing 49 soldiers aboard.
Ukrainian President Petro Poroshenko declared a day of mourning on June 15 over the downing, the deadliest attack yet on national troops since the pro-Russian uprising began in the country's south and east.
Poroshenko said on June 14: "Ukraine is in sorrow, but we strongly continue the struggle for peace."
And in Kyiv, about 100 protesters hurled eggs on June 14 at the Russian Embassy and overturned several parked cars with diplomatic plates, holding a sign saying "Russia is a killer."
At one point, a Molotov cocktail smashed against the side of an embassy building and was quickly extinguished.
The Russian Foreign Ministry condemned the protest, calling the lack of a police response "a grave violation of Ukraine's international obligations" and demanding that Kyiv take steps to ensure its diplomats' security.
The attack on the Ukrainian transport plane in Luhansk came just hours after Washington said it could confirm Kyiv’s claims that Russia has been sending “heavy weapons and military equipment” to pro-Russia separatists in eastern Ukraine.
State Department spokesperson Marie Harf said a convoy of three T-64 tanks, several MB-21, “or Grad” multiple rocket launchers, and other military vehicles had crossed from Russia into eastern Ukraine “near the Ukrainian town of Snizhne” during the last three days -- moving through several towns, including Snizhne, Torez, and Makiyivka.
She also said Washington has "information that Russia has accumulated multiple rocket launchers at this same deployment site in southwest Russia, and these rocket launchers also recently departed."
Denis Pushilin, a pro-Russia separatist leader in Donetsk, told Russian state television on June 13 that separatist had obtained tanks but it was “improper to ask” where they had gotten them.
Pushilin said the tanks were “in Donetsk and are the minimum that we have to defend the city.”
Ukraine's border guard service reported that five Ukrainian border guards died in shootout with separatists in of Mariupol on June 14.
And separatists say they shot down a Ukrainian air force bomber on June 14 after it hit a target in the rebel-held town of Horlivka, in Donets Region. The separatists say the bombing killed one person.