Ukraine's pro-Russian insurgents took a big step toward political reconciliation Tuesday by announcing they will push back disputed local elections into next year in line with Western demands.

The decision was welcomed by Kiev's pro-EU leadership and the Kremlin -- one of the few times the ex-Soviet neighbors have agreed on anything since the conflict erupted last year.

Russia's defense ministry on Tuesday dismissed as "absolute lies" claims that its jets had bombed the Syrian city of Palmyra after Syrian state TV reported the strikes.

"All reports by foreign media that Russian planes have allegedly conducted air strikes against the city of Palmyra are absolute lies," ministry spokesman Igor Konashenkov said, Russian news wires reported.

NATO Secretary General Jens Stoltenberg said Tuesday that Russian violations of Turkish airspace were "not an accident" after Turkey complained of two incursions by Moscow's jets.

"For us, this does not look like an accident, it is a serious violation," Stoltenberg told reporters at NATO headquarters in Brussels ahead of a meeting of the alliance's defense ministers later this week.

Russian military officials were to hold talks with their Israeli counterparts in Tel Aviv on Tuesday after the countries' leaders agreed to establish a mechanism to avoid accidental clashes in Syria.

Israel's military confirmed the two-day meeting on "regional coordination," which comes after Prime Minister Benjamin Netanyahu and Russian President Vladimir Putin held talks last month related to Syria.

Divided over the fate of President Bashar Assad, Arab countries have kept silent over Russian air strikes in Syria, apart from Cairo which openly supports Moscow's campaign, experts said.

"The Arab world has lacked regional leadership for years from within the region, and in that void, the U.S. and Russia have been engaging," said H.A. Hellyer, Middle East policy expert at the Washington-based Brookings Center.

More than 40 of Syria's most powerful rebel factions said on Monday that Russia's air campaign had made a political solution to the country's bloody conflict impossible.

In a statement posted online, 41 groups including Jaish al-Islam near Damascus, Ahrar al-Sham in northwest Syria, and the Northern Front said that Russia's "brutal occupation has cut the road to any political solution".

Germany voiced doubt Monday about Russia's claims that it was targeting Islamic State jihadists rather than moderate rebels with its air strikes in Syria.

"About the... continuing Russian air strikes: We would consider it important to reconcile words and actions," said foreign ministry spokesman Martin Schaefer.

President Petro Poroshenko has stressed Ukraine must regain control of its eastern border with Russia despite an apparent agreement to push back the implementation of a February peace deal into next year.

The Western-backed leader told Ukrainian television late Sunday that he never agreed to the terms announced by French President Francois Hollande at a media event held after summit talks on the crisis in Paris on Friday.

U.S. Defense Secretary Ashton Carter said Monday that Russia is pursuing a "losing strategy" in Syria and that it must live up to its commitments in Ukraine.

Speaking in Madrid at the start of a five-day trip to Europe, Carter told Spanish military officials that by carrying out bombing in Syria, Russia had only worsened the four-year conflict.

Turkey warned Russia on Monday against violations of its airspace by warplanes straying over the border from Syria, as NATO called an emergency meeting over the "unacceptable" intrusion.

Ankara, a NATO member, protested to Moscow after its F-16 jets intercepted a Russian fighter plane that violated its air space near the Syrian border over the weekend, forcing it to turn back.