Oil steadied after its biggest jump in six months as Israel said its retaliation for attacks by militant group Hamas over the weekend had “only started,” increasing the prospect of fresh instability in the Middle East. West Texas Intermediate traded near $86 a barrel after surging 4.3% on Monday, as markets reacted to fighting that started Saturday and reignited a conflict with broad repercussions across the region. Israel has announced its largest-ever mobilization of more than 300,000 army reservists as it attacked Gaza from the air and sea, with Prime Minister Benjamin Netanyahu vowing to “change the Middle East.” Hamas threatened to execute hostages.