Rocket fire tested — but didn't break — a week-old cease-fire between Ukraine and pro-Russian separatists Friday night. The deal has brought the release of dozens of prisoners and cut the number of casualties from fighting, even as both sides have reportedly violated its rules in skirmishes.

Russia has sent a second convoy of trucks bearing what it says is humanitarian aid into Ukraine. Similar to an August operation, neither Ukraine nor the Red Cross reportedly received an early warning about the trucks, and the AP says they crossed the border without being inspected.

Ukrainian defense spokesman Andriy Lysenko called the convoy a "violation of the established procedure of border and customs clearance," according to Ukraine's Interfax agency. He also added, "Representatives of the Red Cross do not accompany the cargo, its contents are unknown."

The incident came as insurgents mounted a fresh attack near the airport in Donetsk, which is under the central government's control.

From Donetsk, NPR's Eleanor Beardsley reports:

"Volleys of GRAD rockets rang out in the night Friday to Saturday in the separatist stronghold of Donetsk, underscoring the difficulties of enforcing the ceasefire a week after it was signed. Later, separatist military trucks were seen driving through the town carrying the rocket launchers."Still, 67 prisoners were released in an exchange between the Ukrainian army and the separatists on Friday, proving that other points of the ceasefire agreement are being adhered to."Despite the progress, the U.S. and European Union hit Russia with tough new sanctions this week in a coordinated response to what they said was Moscow's 'unacceptable behavior' in Ukraine. Russia is accused of supporting the separatists with arms and fighters."

Negotiations for a more permanent peace are continuing. And on Friday, the EU announced it had reached a compromise deal over its plan to expand a trade partnership with Ukraine that has alarmed Russian leaders. The new agreement postpones the full trade pact's implementation until 2016, Ukraine's Kyiv Post reports.

Ukraine's leader criticized Russia's President Vladimir Putin Saturday, calling him a threat to both Ukraine and Europe.

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