US Lt. Gen. Paul Funk greets Kurdish commanders of Syrian Democratic Forces in Manbij, Syria, February 2018

UPDATE, 0800 GMT:

Russia and the regime killed at least four civilians on Tuesday, after breaking their self-declared, four-day “ceasefire”.

The White Helmets civil defense reported the slayings in northern Hama Province and bombing of areas in neighboring Idlib Province, including the “ghost town” of Khan Sheikhoun from which tens of thousands of people have fled.

The Assad regime’s military announced Monday that it was resuming bombing — regime shelling continued on Idlib during the “ceasefire” — after anti-Assad forces refused to withdraw 20 km (12 miles) from a demilitarized zone, which was shattered by a May 6 Russia-regime offensive.

The Russian military issued the pretext that the anti-Assad forces had fired missiles on Russia’s main airbase, Hmeimim in western Syria.

Russian-regime attacks have killed more than 700 civilians and wounded more than 2,200 since late April, and forced at least 360,000 people to leave their homes.

ORIGINAL POST: New Defense Secretary Mark Esper has said the US will block any Turkish cross-border military operations into northeast Syria.

With talks between Ankara and Washington deadlocked over control of the area, held by the US-supported, Kurdish-led Syrian Democratic Forces, Turkish officials have repeated their long-declared intention to send military units into the territory between the Euphrates River and the Iraq border.

On Sunday, President Recep Tayyip Erdoğan declared, “Now we are going to enter east of the Euphrates. We have shared this with Russia and the United States.We can only be patient for so long.”

Esper said Tuesday, “What we’re going to do is prevent unilateral incursions that would upset, again, these mutual interests…the United States, Turkey and the SDF share with regard to northern Syria.”

While Esper said the US would not “abandon” the SDF, he did not offer a guarantee of American protection against Turkish operations.

The US envoy to Syria, James Jeffrey, presented a “final offer” on Monday in Ankara, but no progress was made as talks continued yesterday.

The Erdoğan Government wants 40-km (25-mile) deep zone, with with only Turkish forces ensuring the full withdrawal of the Kurdish militia YPG, the leading faction in the Syrian Democratic Forces. The US is accepting only a zone up to 15 km (9 miles) deep and with joint US-Turkish patrols.

Syria Daily: US “Final Offer” Over Turkey’s “Safe Zone”/Military Operations in Northeast

“A Different Phase Very Soon”

Erdoğan responded to Esper later Tuesday at a conference in Ankara, “We will move the process which we started with the Euphrates Shield [Turkish military intervention from August 2016 alongside Syrian rebels against ISIS] and Olive Branch operations [attacks in 2018 to take most of the Kurdish canton of Afrin in northwest Syria] to a different phase very soon.”

The President, chiding the US to take action “worthy of a true ally” in the fight against “terror”, asserted, “We will defend our national interests by means of soft power, forceful diplomacy or realpolitik as necessary.”

The US created the largely-Kurdish SDF in October 2015, and the Forces finally removed the Islamic State from the northeast this spring. But Turkey considers the YPG militia as “terrorists” who are part of the Turkish Kurdish insurgency, which has fought Ankara’s forces for more than 30 years.

The Kurdish militia is the leading faction in the Syrian Democratic Forces, which has removed the Islamic State from the northeast. Ankara considers the YPG to be part of the Turkish Kurdish insurgency PKK, which has fought security forces for more than 30 years.

Kurdish officials have warned that, if Turkey attacks, they cannot guard prisons with 10,000 captured Islamic State fighters. They say they have agreed with the US military to withdraw three miles from the border.