Prime Minister Benjamin Netanyahu and Russian President Vladimir Putin discussed security problems on Israel’s border with Syria Friday as violence flared in the country's southwest.The Syrian army and its allies bombarded rebels in the southwestern Deraa region on Friday, killing at least six people, a war monitor said, in a region widely seen as a potential flashpoint for further escalation in the conflict. The Syrian Observatory for Human Rights reported that the army had shelled the towns of Kafr Shams and al-Harah, near the border with the Israeli-occupied Golan Heights.It was the highest death toll from bombing since a "de-escalation zone" was agreed in southwest Syria last year by the government's ally Russia, along with Jordan and the United States.According to the Kremlin, Netanyahu and Putin talked about ways to increase coordination with respect to military action in Syria, specifically in that area.The Prime Minister’s Office said that Netanyahu congratulated Putin on the occasion of Russia Day and the decision to hold the official event at Sergei's Courtyard in Jerusalem. The two men also spoke about the opening of the World Cup in Russia.Netanyahu has pressed Russia on the importance on ensuring that Iran and its proxy army leave the area as well as all of Syria.Russia has backed the return of Syrian government forces to that area. On Thursday US State Department spokeswoman Heather Nauert said, “Any Syrian government military actions against the southwest de-escalation zone risk broadening the conflict.”She warned that the “United States will take firm and appropriate measures in response to Syrian government violations in this area.”It is important that Russia, the United States and Jordan do everything they can to ensure a cease-fire in the southwest de-escalation zone, Nauert said.“Russia is duly responsible as a permanent member of the UN Security Council to use its diplomatic and military influence over the Syrian government to stop attacks and compel the government to cease further military offensives. We request that Russia fulfill its commitments in accordance with UNSCR 2254 and the southwest ceasefire arrangement,” Nauert said.President Bashar Assad has sworn to take back every inch of Syria and has been preparing an assault on rebels holding areas in the southwest bordering Israel and Jordan.His military gains in the war have partly depended on support from Iran and allied Shi'ite militias including Lebanon's Hezbollah, which have provided ground forces.Israel wants those forces removed from all of Syria, but is particularly sensitive to their presence near its frontier, and has carried out numerous air strikes against them. It regards Iran as its biggest external threat, and Hezbollah as the biggest threat on its borders.