BEIRUT - Syrian President Bashar Assad has claimed the country's "crisis" is drawing to a close even as his forces unleashed tank shells on opponents and US sanctions took aim at the Syrian leader and his senior aides.

The messages on Wednesday from Damascus and Washington highlight a sharp divide: Western governments trying to boost pressure on Syria, but Assad displaying confidence he can ride it out.

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Assad received a further boost when a call for nationwide strikes fell flat and longtime ally Russia vowed to stand against any UN resolutions that would sanction Syria.

Syria has banned foreign journalists and prevented coverage of the conflict, making it nearly impossible to independently verify accounts coming out of the country or gauge the strength of the unprecedented protest movement in one of the most authoritarian regimes in the Middle East.

On Wednesday, witnesses said the Syrian army shelled the western border town of Talkalakh with tanks for the fourth consecutive day. Syrians fleeing to Lebanon in recent days have described horrific scenes of execution-style slayings and bodies in the streets in Talkalakh.

Activists say at least 27 people have been killed there since last week.

"They are bombing us with tanks, it's been going on for days," a resident told The Associated Press by phone from just outside the town of the town of some 70,000 people, just hours after fleeing.

"Security forces are making random arrests, there isn't one security apparatus that they have not sent to the town," he said on condition of anonymity for fear of reprisals.

More than 5,000 people have crossed from Talkalakh across a shallow river into Wadi Khaled on the Lebanese side of the border in recent weeks.

In Washington, officials said the Treasury Department planned sanctions on Assad and six members of his inner circle. It would mark the first time that sanctions would hold Assad personally accountable for actions of his security forces. In Berlin, Germany's Foreign Minister Guido Westerwelle also pushed for a second round of European Union sanctions that would target Assad.

The Swiss government, meanwhile, passed a measure restricting arms sales to Syria and freezing the assets and banning the travel to Switzerland of 13 senior Syrian officials. The arms embargo is largely theoretical because Switzerland hasn't exported weapons to Syria in over a decade, but any Swiss banks holding assets of the 13 officials will have to declare them immediately to the government.

"The recent events in Syria we believe prove that the country cannot go back to the status quo ante," said White House press secretary Jay Carney. "Syria's future will only be secured by a government that reflects the popular will of its people."

But the Russian president, Dmitry Medvedev, said Assad must be given a chance to fulfill his reform promises and warned against foreign interference in the country.

On Wednesday, Assad was quoted as saying the country's security forces have made mistakes during the uprising, blaming poorly trained police officers at least in part for the crackdown.

Assad's comments, carried in the private Al-Watan newspaper, downplayed the extent of the violence - but they were significant because they mark a rare acknowledgment of shortcomings within Syria's powerful security agencies.

Assad said thousands of police officers were receiving new training and that the "crisis" was nearing an end.

Assad also has blamed much of the unrest of thugs and foreign agitators looking to sow sectarian strife.

Syria's state-run news agency said gunmen killed the head of the Political Security Agency in Homs, Colonel Mohammad Ibrahim al-Abdullah, in an ambush along with four of his assistants Tuesday.

It said a group of young Syrians had announced they want to surrender themselves to the colonel personally, and that when he arrived to meet them, they opened fire, killing him instantly.

Human rights activists also said troops used heavy machine guns to attack a neighborhood in the central city of Homs and sent troops and tanks to Nawa, a village near the besieged southern city of Daraa.

An eyewitness said hundreds of security forces also moved in the town of Dummeir east of Damascus from four sides Tuesday, set up machine guns and were storming houses and making random arrests.

The witnesses said on condition of anonymity because of fear of reprisals.