jerusalem/gaza israeli tank aircraft strike militant position gaza strip thursday soon palestinian militants fire mortar shell israeli military post close territory israeli army say reuters witness gaza say saw smoke rise least two target strike israel one belong hamas another islamic jihad militants witness southern gaza strip say two islamic jihad post hit casualties report initially either side israeli military spokesman lieutenant-colonel jonathan conricus say militants mortar barrage aim israeli army post construction crew work close israeli side gaza border israel construct sensor-equipped underground wall along 60-km 36-mile gaza border aim complete 1.1 billion project mid-2019 conricus say israel look escalate situation israeli action would depend gaza militants least three round airstrikes take place dusk reuters witness say remain ready tool necessary capabilities hand hamas islamic jihad act aggressively ... look escalate situation initiate hostilities conricus say train service israeli town sderot close gaza border ashkelon north briefly suspend resume late even mortar fire exactly month israel blow attack tunnel lead gaza israeli 14 militants kill follow tunnel demolition islamic jihad vow retaliate thursday action first significant reaction last gaza war 2014 hamas fighters use dozens tunnel blindside israel superior force threaten civilian communities near frontier counterpoint iron dome anti-missile system largely protect country heartland militant rocket barrage israel unite state call hamas disarm part pact palestinian authority israeli peace efforts palestinian president mahmoud abbas collapse 2014 could proceed hamas reject demand wednesday abbas fatah hamas agree delay final transfer power gaza hamas western-backed palestinian government 10 days dec. 10 allow time complete arrangements officials say israel strike militant target gaza mortar barrage